What Is Advanced Logo?

In This Issue by Dorothy Fitch When you are 10 years old, 15 seems old. When you are 20 years old, 30 What Is Advanced Logo? : ,. 1 seems old. When you are 30 years old, 45 seems old. "Old" is always older than By 4 you are. Age is a moving target. So is "Advanced Logo". When you first begin Logo Tool Box 6 with Logo, the idea of writing procedures seems advanced. Then variables Logo Users Groups 8 seem advanced. Then words and lists. Then interactive programming. Then New Product Information 8 recursion, the non-tail-end kind. Book Review 9 Advanced Logo is what you don' yet understand. It's something you have Advanced Logo Bibliography 10 to work at, a hurdle, something new to your experience that grinds you to a What is "advanced Logo"? I asked halt. Learning new things can be frustrating, but it's exhilarating when you Dorothy Fitch, , Brian figure them out, understand them, and can use them. Silverman, Alberto Caiias, Sharon It is easy to say that advanced Logois a set oftechnically obscure primitives. Yoder, and . Their These are the less intuitive programming tools, the fancier ''bells and answers comprise the lead article of whistles" of the language. You are probably on your own as you learn these this issue ofLogo Update. As far as I primitives, not generally covered in a typical first Logo course or book. Even know, none of them discussed the experienced Logo users can find "advanced" primitives that they haven't fully question with each other, at least not explored or with which they don't feel totally comfortable (property lists, specifically in connection with this arrays, stream 110, machine language interfacing, bitwise operations). article . Yet there are certain However, in a deeper sense, advanced Logo is not the language, but what viewpoints that several ofthe authors you do with it. People sometimes call Terrapin and ask for our "easy" version share. Seymour Papert reflects on of the language. There is no "easy" version. There is no "advanced" version. those themes in his commentary There are just "easy" or "advanced" things you can do with Logo,just as there beginning on page 4. are "easy" and "advanced" things you can do with a hammer, nails, and wood, If you are about to put this issue of or with a needle, thread, and fabric. Logo Update aside because "advanced What makes a project "advanced?" It might require more complex problem- Logo"is not for you, I suggest that you solving strategies. It might be a program with scores of procedures, creating give it a chance. The various many paths through it, more opportunities for bugs to creep in, and more perspectives ofthe authors collectively testing routines. It may be an elegant but simple program that shows a full convey a view of advanced Logo that comprehension of recursion. is inclusive and not at all elitist or An "easy" Logoproject can become an "advanced" project simply by changing obscure. the rules: "Do this using only five instructions." "Find a way to solve this Carol Sperry's Book Review recursively." "Do this without using the following primitives: ... " "Solve this continues that theme with a look at problem in three different ways." Sometimes advanced projects push you into several advanced Logo books. learning primitives you might not have otherwise investigated, bringing Accompanying the review is a together both ways of looking at "Advanced Logo". bibliography of books and papers Logois a set oftools. You learn to use them at your own pace; you make with suggested by Carol and by the other them what you want. And if your Logo contains the tools for the projects you authors. want to complete, then that's all you need. Unlike most computer environments, I puzzled for a while about how to Logo continually offers new challenges to those who seek them. sequence the six pieces that form the main article. Since my name begins by Brian Harvey with "T" I never liked the idea of This feels like a funny question to me, since the party line these days is that listing authors in alphabetical order. In Logois a tool to be used for studying other things, and if that's so, the emphasis the end, I arranged them randomly. should be on, let's say, advanced math rather than advanced Logo. (Yes,ofcourse Iused aLogoprocedure. Nevertheless, there's a paradox in Logo-as-tool, namely that unless you It's on page 7,but why don't you try it study Logo itself, it's not a very transparent tool. Logo beginners can get for yourself before looking there?) trapped in small details of syntax, which make it hard to get past the mechanics of programming into the math or whatever else you're trying to learn about. If you say "I'm not interested in Logo itself," you never overcome this vulnerability to the syntax. There are two ways to solve the problem of programming details. One is for some expert, a teacher or a Logo implementor, to build a simplified interface (Continues on next page) page 2

Logo Foundation as long as you can remember every as successive versions of Logo have 250 West 57th Street detail of your program. But as let more and more things be New York, NY 10107-2603 programs get larger, they get much:" increasingly concrete. (For instance, Telephone: 212765-4918 harder to debug, because the result of when LogoWriter came out I started FAX: 212765-4789 this instruction depends on some printing to the page to keep lists of email: [email protected] leftover result from another results instead of using sentence to instruction 300 lines away. Partly keep lists of results.) What's grown Board of Directors Seymour Papert, Chair this kind ofadvancement comes from instead is the sophistication of the Clotilde Fonseca practice: from writing lots of ideas I've let myself explore and the Tessa R. Harvey programs. But there are ideas that range of interests that I've mucked Geraldine Kozberg programmers can learn to help control about with using the computer. Over Michael Tempel the complexity oftheir programs; the the last couple of years the projects Takayuki Tsuru most important of these ideas is have usually had something to do The Logo Foundation is a nonprofit abstraction, which means extending with experimental mathematics or educational organization incorporated the vocabulary ofyour programming evolutionary biologyor whatever else in New York State. language by inventing new features, managed to catch my interest. new data types, and so on, and then Using programming as part of an Logo Update is published three times using those extensions to make your exploration requires a certain amount yearly by the Logo Foundation. program shorter and cleaner. (It was of fluency. Fluency in the sense of Subscription is free. because BASIC didn't provide the being able to create Logo programs © 1994 Logo Foundation language extension tools needed for while thinking about the exploration You may copy and distribute this abstraction that Logo people fought rather than thinking about Logo or document for educational purposes against it back in the early days of the computer. This comes with provided that you do not charge for educational computing.) practice, with looking at examples, such copies and that this copyright notice is reproduced in full. Finally, of course, some of those with discussing "neat hacks" and extra features that help you write tricks of the trade with friends and (Continued from page 1) more complex programs are already mentors, with essentially the same that you can use to get at some set of in Logo, so "advanced Logo" also kind oflearning strategies that you'd ideas without really using the Logo means learning about property lists, use to pick up any other non-trivial _ language.Il'he.other.iand.here is.the, about-procedun~"as-data.(define-and -sk-ill.-Thekind-offl-uefl.BYthat-lets you paradox, is to invest some effort into text), about nonlocal exit (catch and express yourself without thinking Logoas an object ofstudy, so that the throw), about parallelism in LCSI's about the language is for me what language truly does become a MicroWorlds, about object-oriented advanced Logo really is. transparent means of access to ideas programming in Paradigm Software's about other things. Object Logo, and so on. by Alberto Canas So I'd say that one meaning of Advanced Logo can refer to an "advanced Logo"is reaching a state of by advanced use of Logo or to an mind in which the syntax rules feel It's often hard to get a handle on advanced version of the language. I sensible rather than arbitrary. Why what "advanced" means. I remember propose that any truly advanced do you put quotes in front of the someone telling me a story about version of Logo must lead to an variable name with make but a colon asking a bunch of children what they advanced use of the language. in front with print? A beginner will thought advanced mathematics were. The first idea that too often comes say, "Generally you use the colon for The answer was usually something to mind when considering the phrase variables, but make is an exception." like doing sums. But it was sums of "advanced use ofthe language" is the An advanced Logoite will say, "It has really big lists of really big numbers. complexity of the instructions used nothing to do with make or print, I suppose we could use reasoning in programming: the more complex really. When you use make, you like this to say that advanced Logois (or "advanced") the instructions, the generally (although not necessarily) writing really big programs filledwith more advanced the programming, and want to use the name of a variable as long, complicated, exotic commands. thus the more advanced the use of its input, and that's what the quote In fact, for some people, as the years the language. But, is the "use ofmore means. But when you use print, you go by, the programs that they write advanced instructions" in a usually (but again not necessarily) get bigger and sometimes they also equivalent to are using the value of the variable as get more complex. a more "advanced use" of the its input, and that's what the colon I don't think that this has been the language? means." case for me. When I look at the We can consider two types of To me, "advanced Logo"also means programs that I've written for myself, complexity: the complexity of a being able to write a program that's they haven't grown much in either program and that of the problem to too big to fit in your head all at once. size or complexity. In fact they may be solved. The complexity of a is pretty easy have evenbecomeshorter and simpler program is subjective; what appears

Logo Update / Winter 1994 page3

to be a complexprogram to one person perspectives. First, Advanced Logo About the Advanced may be simple to another. may refer to using the existing Experienced programmers, for features of Logoin such a manner as Logo Authors example, analyze and recognize to provide clean and elegant solutions "chunks" ofcodeinstead oflooking at to an increasingly complex set of Dorothy Fitch is Director of individual instructions as novice problems. Secondly, the term Product Development at Terrapin programmers do, and therefore can Advanced -Logo may refer to the Software. A former music teacher, more readily understand what a long constructs which we add to the she has also written several Logo program does. A deeper language in order to solve a wide tool packages including the Logo understanding of the problem being range of problems in a cleaner and Data Tool Kit and KinderLogo. solved may also render the program more elegant manner than previously less complex. It is thus inappropriate considered possible. Brian Harvey is Lecturer in to talk about the advanced use of a at the University language by discussing program by Sharon Yoder of California at Berkeley. He also complexity. As editor of the Logo Exchange I taught computer science for many Complexity can also be attributed often encounter "advanced Logo." years at the high school level and is to problems. Although this complexity Potential authors write to tell me of author of the three volume is also subjective, it is independent of the "advanced" work their students Computer Science Logo Style. the instructions used in solving the are doing. Others submit "advanced" problem. A simple set ofinstructions articles for one column or another. Brian Silverman is President of may be an elegant solution to a very And yet others describe some LogoComputer Systems, Inc. where complexproblem, while a complicated columnist's work as "advanced." he has been responsible for the and obscure set of instructions may But what, indeed, is an advanced design and development of many be an inefficient solution to a simple user of Logo?I often ask myself that versions of Logo including problem. Although there may be more question when I teach a Logo class. MicroWorlds, LogoWriter, and the than one "best" solution to a problem, Some of my students seem destined Phantom Fish Tank. any clean and elegant solution will to be "advanced" Logo users and employ the available features of the others do not. Why? I believe the Alberto Canas is Assistant language in the most appropriate answer lies in an understanding of Professor of Computer Science at way. Therefore, the design of clean Logo that goes beyond the specific the University ofWest Florida. He and elegant solutions to problems version being used. Let's examine has been involved with the accurately reflects an advanced use some examples: An advanced user introduction ofLogointo schools in of the language. will try something like cs to clear the various Latin American countries But clearly there will always be screen, and if that doesn't work, will while working with the IBM Latin problems which could be solved more try commands like cg, cleartext, American Research elegantly if the programming clean, and home. An advanced user Center in Mexico. He currently language offered a new construct has enough understanding of leads Project Quorum, a which it does not currently contain. different versions of Logo to try partnership between IBM and the The features that Logo provides different possibilities. An advanced University of West Florida to therefore have a direct effect on the user is undaunted by differences in establish a communications quality of the solutions a user can syntax. So if if:a < :b then forward network among schools in Latin design, and should thus be considered 10 else back 10 doesn't work, then America. when talking about an Advanced variations such as if:a -c rb [forward Logo. However, just adding features 10] [back 10] will be tried. Sharon Yoder is Editor of Logo to Logo does not make it a more A combination of familiarity with Exchange. She has taught Logo at Advanced Logo. In programming more than one Logo dialect and the high school and college levels language design, the problem is not understanding of the way in which for many years and is the author of only to carefully select which Logo processes commands and several Logo books including constructs to add to the language, operations allows advanced Logo Introduction to Programming in but more importantly, to carefully users to make intelligent guesses as Logo. She currectly teaches select what to leave out. Any new to the correct syntax. Further, an computer education courses at the feature should allowthe user to design advanced Logo user deciphers error University of Oregon. an even cleaner and/or more elegant messages and uses the information solution to the problem at hand. And contained in them. So for example, Mitchel Resnick is assistant such a feature should be usable over when typing setpos 23 45 gives the professor at the Media Lab at MIT. a wide of range of problems with message setpos doesn't like 23 as He is one ofthe inventors ofLEGO varying degrees of complexity. input, instead of repeated random Logo, the creator of Star Logo, and In summary, it is appropriate to trial and error, the advanced user has taught Logo to people of all speak of Advanced Logo from two (Continues on next page) ages for many years. ---======;::===;:;::::;::=::::;::;:;;::=:::;::;-:;:::: Logo Update / Winter1994 page4

(Continued from page 3) thinks about the possible meaning of the message and tries appropriate alternatives. When beginners first learn Logo, they are very sensitive to the particular version and the syntax and When Michael Tempel asked me whether I would respond to responses to semantics of that version. the question ''What is advanced Logo?"I secretly hoped for a fight. But when Unfortunately, too few users move the statements came, my initial disappointment at their non-belligerent beyond that level of understanding. tone soon gave way to an enjoyable sense of having acquired from them a Such users constantly ask for rules to more advanced sense of "advanced." And the opportunity to spend an hour translate from one version to another with a fourth grade class in between writing my first draft and this draft or become completely overwhelmed allowed me to feel quite concretely how this acquisition could give rise to by minor differences in commands. advancement in my skill as a Logo teacher. Thank you, Michael, for a very As a teacher of Logo, my goal has good idea. always been to prepare students to be Every teacher has (more or less consciously) developed strategies for advanced users. I have always tried responding to a set ofintellectual statements. Among my own, the following to get them to look beyond the were drawn out when I thought about writing this piece: particular version they were using to Classify: Make a taxonomy of the various positions. the structure of the language itself. I have always tried to expose them to Theorize the taxonomy: Make up explanations of why who says what. several dialects of Logo. If you are a teacher of Logo, consider exposing Quibble: Even if you agree with most of what everyone says, exploring your students to more than one objections creates a tension that contributes to energizing intellectual work. version ofLogo. Even ifthey only see a different version in class, such Appropriate: However many objections to an idea you have found, think exposure will help prepare them for about how you can use it. the inevitable day when they find a· . . . h . di I Personalize: However much you hke the language of the original author, program t. ey want to use III a ia ect recast it in another way. ofLogo_dlfferentJroIlLthe....nn€-that_ _ _ ~ __ _ _ they learned. (Continues on next page) by Mitchel Resnick need it more than anyone (and many what other ways can Logo become What is meant by "advanced Logo"? are shocked to find that most more "advanced"? My intuition is to Are we talking about "advanced" programming languages don't allow look at other types of "multi." In features in the language? Or it!).When children make video games traditional Logo activities, one "advanced" programs written in Logo? in Logo, they want to make many student sits in front of one computer Or "advanced" project ideas? Or characters move at the same time. using one process to control one object "advanced" ways of thinking When they create an amusement park (the turtle) inone medium (graphics.) encouraged by Logo? in /Logo,they want to make all Many new opportunities arise if we And what dowe mean by "advanced" of the rides move at the same time. change each one to many - that is, if anyway? If "advanced" means that Multi-processing makes that possible. we develop Logo activities involving only a small handful of people can do At the same time, multi-processing many users (communicating over it, then I'm not very interested. I'd can encourage the development of networks), many objects (thousands like "advanced Logo" to be more new ways of thinking, new of turtles, for example), many accessible, not less so. If we're going epistemological stances. When processes, and many media. And, of to advance, let's all advance together. students see patterns in the world course, we should make sure to In my mind, advanced Logo should (like a flock of birds), they generally support and encourage many different enable more people to make more assume that someone or something is thinking styles. things more easily, and it should in charge (the "leader bird"). But as This multitude ofmulti-ness might engage more people with more students play with multi-processing seem overwhelming. Indeed, more is powerful ideas in the process. In short, versions of Logo (such as LCSI's not always better. But my hunch is advanced Logoshould encourage new MicroWorlds, or my own StarLogo), that these new forms of multi-ness ways of making and new ways of they can begin to see the world in new could (in the appropriate contexts) thinking. ways. They can begin to understand make Logo activities more personal, The addition ofmulti-processing to how patterns can form through more connected with children's Logo offers an example of how that's multiple interactions, without any interests, passions, and experiences. possible. In the computer science centralized control. And, at the same time, they could community, multi-processing is seen Multi-processing, of course, is just help children develop new ways of as an "advanced" feature. But children one aspect of "advanced Logo." In looking at the world..•. Logo Update / Winter1994 page5

(Continued from page 4) an important distinction (a sub- large extent, cannot be used well Dorothy Fitch articulates most subclassification) within (b)is brought without being understood. People explicitly a relativistic position that out by thinking (bl ) of a Logoist often cite the hammer and the could be expressed as: One Logoist's coming to use more primitives and automobile as tools that don't have to advanced is another's elementary.* (b2) a Logoist coming to think be studied as objects. But this is She is suggesting that one should differently about the primitives being because relevant knowledge is so think about advancing as a process, a used. embedded in our cultures that we direction of movement, rather than The last distinction is very relevant don't recognize it as knowledge. advanced as a destination or terminal to a view of advanced vs. elementary I'd take this a step further: we can state. But whether one opts for that is far more strongly represented use hammers sowellbecause weknow continuous movement or for in thousands of classrooms than in a lot about nails. Knowing about the discontinuous jump, there is a further the discussion of the sophisticated tool and knowing about the use are subclassification based on what it is people writing here. Many teachers not easily separated. I am prepared that moves (or jumps). have been taught to think in terms to quibble about the distinction Mitchel Resnick most cleanly opts like: elementary Logo is about between using Logo in a more for Logo as the moving object; his graphics primitives; advanced Logo advanced way versus usingitformore discussion of "advanced Logo"refers is about lists. This definition can't be advanced purposes say to a changed Logo rather than the taken quite literally, since a list is mathematics. Maybe a central same Logoused in different ways. Of present in instructions used by component of what makes course, given that his own work has beginners such as repeat 4 [fd 50 rt mathematical thinking more been so largely concerned with 90]. But a more modulated form of "advanced" is exactly the same creating new forms of Logo, it is not the distinction can be cast in terms of reflective attitude that makes Logo surprising that change in Logowould steps that mark a direction of thinking more advanced. be most salient in his response. For advancing such as the followingthree From this point of view the most the same reason one is not surprised stages. In stage 1the [,',] used in a important criterion for judging the to recognize in Brian Silverman's repeat instruction is an unanalyzable evolution of Logo might be whether piece a similar emphasis, though in cliche without any list-related the change advances the ways in his case it is secondary to what he meaning. In stage 2, understanding which Logoists think about Logo. shares with Brian Harvey, Alberto instructions like repeat 4 readlist There are many allusions in the Canas, and Sharon Yoder who talk of shows that repeat is actually seen as papers to how this might happen. An the movement of the Logoist rather a primitive with two inputs, a number unexpected one was Sharon Yoder's than ofthe Logo- movement in Logo and a list. Stage 3 is marked by being observation that students with an rather than movement of Logo. able to discuss reasons for choosing advanced attitude enjoy comparing The advancing movements of Logo's syntax, rather than simply different versions of Logo - I'd add Logoists are classified by all the using repeat 4 fd 50 rt 90. A major that the cause and effect here is a commentators (though in subtly fallout for me of writing this column two-way street: playing with the different ways) into two subclasses is a decision to think a lot about how differences also fosters the growth of exemplified by (a) someone who uses to incorporate such discussions more the "advanced" way of thinking. A the same set of Logo primitives, explicitlyin teaching Logoat all levels: more deeply controversial case is methods and ways of thinking to Let's have more talk about why Logo Brian Silverman's reference to tackle more complex projects and (b) is as it is and how it came to be so. directions of development that favor someone whose progress is seen not This resolution appears to place me greater concreteness in thinking. in the projects tackled, but in the way in the taxon defined by advancing the A distinction between epistemo- Logo is used to tackle them. Finally Logoist rather than the Logo, and logical and instrumental criteria advancing in thinking about Logo pervades Mitch Resnick's discussion rather than in what you do with it. of what is more advanced about new * Two lingusitic observations: Brian But it is quibble time for the versions of Logo. Multi-processing is Harvey says "Logoite" where I say classification. Brian Harvey (whose an advance because it allows more "Logoist." I couldn't decide whether reference to make and quote exactly people to do more things. It is also an this reflects a different view of Logo parallels my repeat and [ ]) refers to advance because it facilitates ways of users, a difference in taste in the distinction as a paradox for the thinking. I use it as a springboard to linguistics, or a mere "neutral" "party line" view that favors thinking end with a question that will allow accident. The commentators are ofLogoas a tool. Mysense ofthe party lots of quibbling. collectively shy about using a word line is that indeed the way tointroduce It is obvious to me that Logo for the opposite of advanced. Is this because elementary has Logois as a tool with lots ofuses. But requires and facilitates ways of (unfortunately) acquired a I see nothing paradoxical in a firm thinking about itself and about other pejorative connotation? Or another focus on the fact that all tools to a stuff. But does it do these goodthings neutral accident? large extent, and this tool to a very to one fundamental way of thinking (Continues on next page)

LogoUpdate / Winter1994 page 6

(Continued from page 5) or to a multitude of them? Talking about movement of Logo, Mitch Resnick and Brian Silverman pick In her article in this issue ofLogo Update, Dorothy Fitch defines advanced what looks like different features. Logo as "...what you don't yet understand." But not understand~ng enough But I see the abstract-concrete tension Logo to write acertain procedure doesn't mean that you wouldn t be able to in the galaxy of possible mindsets as make good use of it if you had it. intimately related to the centralized- Young children may not understand how to write proc~dures to draw decentralized mindsets and both as squares, triangles, or circles, but many Logo teacher~ give them such related to hard-soft, hierarchical- procedures as "tools" to enrich their drawings and give them greater heterarchical and a host of other satisfaction in what they can do with Logo. (And, they may also learn to slants on multiple ways of knowing recognize and name various geometric shapes.) that have become prominent (if not Tools can fill the gap between what you can make for yourself and what faddish) in the recent discussions of you need in order to accomplish your goal~. If we look closely. at what alternative espistemologies. Is it students are attempting to do as they work WIth Logo we can provide them possible that on the deepest level with appropriate tools they need for their projects. . there is one direction in which Logo Recently, in Costa Rica, I watched a number of students work on projects facilitates thinking? I understand that included drawings of "carretas." These brightly painted wooden how this very question might appear oxcarts have large wheels that are decorated with geometric designs to be a proofthat I have not been able radiating from the hubs. A useful tool came to mind. to break away from the "canonicalist" Most often, people use a Logo instruction such as this to draw a circle: mindset - even in rejecting one canon I can't resist looking for another. But this may not be so bad if the canon is repeat 360 [fd 1 rt 1] based on extending the principle with which Alberto Canas ends his paper: the only really advanced Logo would be one that would allow the Logoist to o The turtle begins and ends at a point on the circumference of the circle. reject anything and everything about It's not so easy to find the center. Here's a procedure that draws a circle of it-by building his-own ..• -- a given radius, centered at the turtle's position:

to circle :radius pu fd :radius rt 90 pd repeat 360 [fd (3.1416 * 2 * :radius) / 360 rt 1] ~~pu 90 bk :radius 8ii' end

After the circle is drawn the turtle is back at the center. Now you can draw spokes or other designs that emanate from the hub.

circle 50 repeat 12 [fd 50 bk 50 rt 30]

You could use circle as a starting point for a program to draw pie charts. It's also good for drawing concentric circles. . . ., But I thought of a problem. What if! draw a CIrcleand then decide It s too big or too small? I'd like to be able to undraw it by drawing it again in penerase mode:

circle 40 oops! pe circle 40

Logo Update / Winter 1994 page 7

But the second circle 40just draws a circle again because the pu and pd commands within the procedure override the pe command. Actually, these pen commands do not work the same way in all versions of Logo. (I was working in Logo Writer.) In Terrapin Logo for the Macintosh the pen's drawing mode is independent ofwhether it is up or down. The procedure I wrote actually does work either to draw or erase, depending on whether the last pen mode command was penerase orpenpaint. In Object Logo I modified circle like this:

to circle :radius make "pen penmode pu fd :radius rt 90 setpenrnode :pen repeat 360 [fd (3.1416 * 2 * :radius) I 360 rt 1] pu It 90 bk :radius setpenrnode :pen end The procedure remembers the pen mode before doing anything else, restores it before circling, and again just before ending. In Logo Writer a second procedure is needed to erase circles:

to erase.circle :radius pu fd :radius rt 90 pe repeat 360 [fd (3.1416 * 2 * :radius) I 360 rt 1] pu lt 90 bk :radius pd end

Shuffle

Here's the Logoprogram I wrote to randomize the order ofthe six authors ofthe advanced Logo articles in this issue of Logo Update. Before I began working in Logo, I thought about several models of shuffling a deck of cards. Split the deck into two piles and then mix them back together. Throw them up in the air and then pick them up after they land. I settled on a simple model that I felt would work well in Logo: Pull a single card from some random place in the deck and put it on top. This move, in itself, doesn't mix things up very much, but repeating it a few times does the trick.

to shuffle :deck output move.to.top (pick. from :deck) :deck end

to move. to. top :item :stack output sentence :item (remove :item :stack) end

to remove :it :them if :it = (first :them) [output butfirst :them] output sentence (first :them) (remove :it butfirst :them) end

to pick. from :group output item (1 + random count :group) :group end

Print shuffle shuffle shuffle shuffle shuffle [Canas Fitch Harvey Resnick Silverman Yoder] Fitch Harvey Silverman Canas Yoder Resnick

There are many ways to shuffle. How would you do it? .&. Logo Update / Winter 1994 .--.----.-.~~~~~----~~-

page 8 NEW PRODUCTS

The Logo Foundation is offering several new publications. You may use the response form on page 11 to order them. A Full-Screen LogoWriter Printshape Procedure by Tom Trocco allows large display and printing of turtle shapes. A LogoWriter Ecology Simulation by Tom Trocco explores interactions between plants and animals in a pond. Headlight Stories is a collection of writings by teachers at the Hennigan School in Boston about their experiences during eight years of Project Headlight.

MicroWorlds Math Links'P', the third product in the MircoWorlds series, has been released by Logo Computer Systems, Inc. It includes the same new version ofLogoas Micro Worlds Project Builder ™and Micro Worlds Language Art ™ along with more than two dozen activities with polygons, patterns, permutations and combinations, and transformations. Call LCSI at 800 321-5646 for more information and a free demo disk. Navajo textile design created using MicroWorlds Math Links Object Logo 2.70 ™ has been released by Paradigm Software. Free to current Object Logo users, this upgrade includes 32-bit addressing, a new Learn More About , and a new applications generator. For more information contact MicroWorlds Project Builder Paradigm Software at 617 576-7675.

On March 12, 1994 LCSI is offering SoftEast Corporation has announced the release of WIN-LOGO for a free Micro Worlds Project Windows™. This new version incorporates the features of the earlier Builder" workshop in St. Louis, MSDOS-based WIN-LOGO, but takes full advantage of the MicroSoft MO. Call for details. Windows environment. Also available from SoftEast is the WIN-LOGO/ LCSI 800 321-5646 LASY Robotics System, a construction kit consisting of plates, blocks, gears, wheels, sensors, switches, lights, motors, and other elements. Electro- mechanical models may be controlled using WIN-LOGO. For more Logo Users Groups information call SoftEast at 508 897-3172. Long Island Logo Users Group Contact: Marilyn Tahl LEGO Dacta has announced the spring 1994 availability of Control 516 333-4018 (evenings) System which combines LEGO®elements, sensors, lights, and motors with 516627-8110 (days) the same computer interface and Logo-based software as the recently released Control Lab+". Science and math curriculum materials for the Los Angeles Logo Users Group upper elementary grades are provided with Control System. A Macintosh January 25 • March 15 • May 24 or MSDOS computer is required. Contact LEGO Dacta at 800 527-8339. Time: 4:00pm-7:00pm Campbell Hall Crystal Rain Forest ™ has been introduced by Terrapin Software. This 4533 Laurel Canyon Blvd. adventure game teaches Logothroughout, and provides for learning about North Hollywood CA 91607 environmental topics. It incorporates Crystal LogoTM, a simplified Logo, Contact: Carolina Goodman which may be used separately as well as within the game. Crystal Rain 213 980-7280 ext. 234 Forest won the British Educational Technology Gold Award in 1993 for New York Logo Users Group Best Primary Software. Contact Terrapin at 800 972-8200. February 8 • April 12 • June 7 Contact: The Logo Foundation The International Society for Technology in Education has announced 212 765-4918 the publication of a series of three books by Gary Flewelling: Math Activities Using LogoWriter Philadelphia Logo Users Group -Patterns and Designs Contact: Mel Levin -Investigations Prince Hall School -Numbers and Operations Godfrey and Gratz Aves. Each volume includes lessons, worksheets, and disk-based activities. For Philadelphia PA 19141 more information contact ISTE at 800 336-5191 ..•. 215276-5369

Logo Update / Winter1994 page 9

JB(Q)(Q)Jk ~eview by Carol Sperry Computer Science Logo Style: though some can be rather difficult, itself a "scientific approach into Volume 1:Intermediate are filled with thought-provoking and English." The effort, however, was Programming imagination-expanding ideas and can well worth it since it's a playful romp Volume 2: Projects, Styles, be digested, if necessary, a little at a through linguistic notation and fulfills & Techniques time. I have wished from time to time its authors' humblest wishes that we Volume 3: Advanced Topics that these specialized books could go at least find the book " 'merely' by Brian Harvey, MIT Press, through some kind of so enjoyable, interesting, and Cambridge MA, 1985, 1986, 1987 that generalist teachers could take stimulating." Using Logo programs advantage ofthe powerful ideas they as the notational system for theories Exploring Language with Logo contain. But then I wonder what about language allows us to make by E. Paul Goldenberg and Wallace would be lost in translation and how simple hypotheses, try them out, and Feurzeig, MIT Press, Cambridge important a part of the endeavor is make changes easily as our findings MA, 1987 the challenge to understand. grow more and more complex. As Brian Harvey's trilogy Computer stated in the introduction ofthe book, Visual Modeling with Logo Science Logo Style offers a rich "The chance to experiment - to try by James Clayson, MIT Press, environment of ideas. I stuck for the out ideas concretely and see how they Cambridge MA, 1988 longest time with Volume 2: Projects, work ... fundamentally changes the Styles, and Techniques. Though nature oflinguistic exploration. The I'm going out a bit on a limb with described as suitable for the enterprise ... becomes more dynamic, this review forLogo Update and admit intermediate learner, I found I could and this makes it more accessible to that I've had to quash some follow the procedures, use them as more people." A great feature of intellectualinsecurities to broach the models, and goon from there. Harvey Exploring Language is experiencing, topic of advanced Logo. However, it wrote the book in a case study format through their writing, the authors' was some of these same intellectual and created each project for the palpable love of language in all its insecurities that kept me, for some enjoyment of it, "not because it fit complexities. time, from some ofthe pleasures that some subtle pedagogic purpose." Finally, I'd like to say a few words can be found in this part of the Logo Project topics include cryptography, about Visual Modeling with Logo by landscape. games, mathematics, programming James Clayson. This is a delightful There are many different answers utilities, and pattern matching. exploration into problem solving to the question, "What is advanced Harvey's discussions of the projects through visualization. Clayson found Logo?",some of which appear in this are broad and once I was involved, that "visualizers seemed . . . less issue's pages of Logo Update. Brian his style helped me feel as though I intimidated by vagueness because Silverman, for example, supports . were in conversation with the author. their picture-making abilities gave doing advanced Logo projects using He asks questions and then takes us them concrete starting points, and simple Logo commands and through the process of the answers, they seemed to enjoy playing around procedures. Brian Harvey approaches giving us detailed narratives of his with the painted pieces of complex the subject from a computer science own explorations ofthe projects. The problems." He wondered if "their perspective. But what does the two other books in this series are visual play encouraged them to see average teacher think about advanced Intermediate Programming, which where more analytic approaches Logoand does she think she can ever introduces Logo from a computer might usefully be applied." The book get to that phase? science point of view, and Advanced is an outgrowth of the courses he I was a teacher for many years in Topics, which introduces some ofthe devised to teach visual thinking to the New York City public school elements ofuniversity-level computer students who had problems doing it system, and then a teacher ofteachers science, still in the context of Logo naturally. in various places. I have found that programming. Clayson's style also invites you in, the average teacher often gets too In 1987, E. Paul Goldenberg and to discover with him, and then to bogged down in the day-to-day ofher Wallace Feurzeig published explore on your own. Like the books practice and is sometimes uneasy Exploring Language with Logo. I mentioned above, this is not a book about getting involved in the so-called was excited about this since I consider about Logo,but one which used Logo advanced Logo books. For years, I myself more of a language person to dosomething else. Visual Modeling bought many of these books but was than a math type. Once again, I felt shows us a fascinating array of too daunted by what I thought I'd somewhat hesitant as I looked into designs including fractals, Islamic find in them or, to be perfectly honest, the book since it seemed more like a patterns, considerations of objects in somewhat fearful offinding myself in romp through linguistics and called (Continues on next page) Logo Update / Winter1994 page 10

(Continued from page 9) aspects there are to the act of seeing. expertise. I was often surprised to space, and using variously shaped The books mentioned here are just find that seemingly unrelated Logo grids. Clayson welcomes us to "copy a few of the broad range there is to .information cleared up other areas of the ideas of any procedure" and then choose from. (You'll find more titles programming I was having trouble to "play rough with them," giving listed in the box below.) with. If you are suffering from the "the copied procedure funny and Of course, there is the question of same lack of confidence that I had, I outlandish arguments." Ideas are Logofluency;to doanything else while hope these few paragraphs will used from the worlds of design, using Logo, you have to know Logo. encourage you to plunge in and not aesthetics, math, art, science, and However, I have found that, bit by deprive yourself of the pleasures of even psychology. The wide range of bit, my repertoire of Logo know-how so-called advanced Logoadventures. exercises allows us a rather thorough was greatly increased each time I ••• personal investigation of the many ventured into other realms of Advanced Logo Bibliography LOGO BOOKS Lewis, Philip G., Approaching Precalculus Abelson, Harold, and diSessa, Andrea, Turtle Mathematics Discretely, MIT Press, 1990. Vectors, Geometry, MIT Press, 1981. A well-known classic, transformations on the plane, graphs of functions, with a very advanced look at the mathematics behind limits, and other such topics. the graphics. Resnick, Mitchel, Beyond the Centralized Mindset: Birch, Alison, The Logo Project Book, Terrapin Explorations in Massively-Parallel Microworlds, Software, Inc., 1986. Logo projects with words and MIT Press, 1994 (expected availability by fall 1994.) lists. The ideas underlying StarLogo, in which thousands of turtles can move and interact in parallel, and how it Boecker, Heinz-Dieter, Eden, Hal, and Fischer, encourages thinking about decentralized phenomena. Gerhard,Interactive Problem Solving Using Logo, Lawrence Erlbaum, 1991. Case studies of interactive Silverman, Brian, Phantom Fish Tank, LCSI, 1987. problem solvingin fields such as mathematics, artificial An exploration of cellular automata, this is John intelligence, and linguistics. Conway's Game of Life carried to its ultimate conclusion. Includes a specialized version of Logo. Clayson, James, Visual Modeling with Logo MlT Press, 1988. Geometric activities such as tiling, with Solomon, Cynthia, Computer Environments for detailed attention to actual patterns used in different Children MIT Press, 1985. A research document cultures. describing and comparing four different approaches to the use of computers in education, including Logo. Cuoco, Albert, Investigations in Algebra, MIT Press, 1990.Examples mainly from combinatorics and COMPUTER SCIENCE LOGO STYLE number theory used to develop ideas in abstract WITHOUT LOGO algebra. Abelson, Hal and Sussman, Gerald, Structure Friendly, Michael,AdvancedLogo, A Language for and Interpretation of Computer Programs, MIT Learning, Lawrence Erlbaum, 1988. Logoas a "real" Press, 1984 programming language and as an educational methodology. Harvey, Brian and Wright, Matthew, Simply Scheme: Introducing Computer Science, MIT Goldenberg, E. Paul, and Feurzeig, Wallace, Press, 1994 Exploring Language with Logo, MIT Press, 1987. Linguistics topics, exploring the structure of large PAPERS units (poems) down to small units (sound and spelling of words.) Silverman, Brian and Tempel, Michael Fuzzy Logo, Logo Foundation 1985. Introducing randomness into Harvey, Brian, Computer Science Logo Style A the world of turtle geometry opens the door to three-volume series: 1. Intermediate explorations offeedback, probability, and statistics. Programming 2.Projects, Styles, and Techniques 3. Advanced Topics MIT Press, 1985, 1986, 1987. Silverman, Brian and Tempel, Michael Creating a The first volume is a Logoprogramming text with the Logo Tool Box, Logo Foundation 1988. Learning emphasis on list processing. The second is a collection more about Logowhile writing Logoprocedures for the of ten programming projects with commentary. The primitives you don't have. third is the first week of six college courses, from automata theory, through , to artificial Tempel, Michael, Conversations with Logo, Logo intelligence. Foundation, 1989. Logoanswers some questions about how she works. Hoyles, Celia, and Noss, Richard, Learning MathematicsandLogo,MITPress, 1992. Acollection Tempel, Michael, Easy as 11223, Logo Foundation, of research papers about various aspects of the use of 1988. An exploration in number theory using Logo. Logo in math classrooms.

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Enter my order for: quantity amount o Turtle Geometry $37.50(HB) $19.95(PB)...... $ _ o The Logo Project Book 0 PC Logo 0 Logo Plus for the Apple II $29.95 $ _ o Interactive Problem Solving Using Logo $79.95(HB) $39.95(PB) $ _ o Visual Modeling with Logo $19.95 __ $ _ o Investigations in Algebra $47.50(HB) $29.95(PB) __ $ _ o Advanced Logo $89.95(HB) $39.95(PB) _ $ _ o Advanced Logo Disk $29.95 0 LCSI Logo II 0 IBM Logo __ $ _ o Exploring Language with Logo $21.95 __ $ _ o Exploring Language with Logo Disk $15.95 0 Apple Logo 0 Mac Logo 0 IBM Logo 0 Terrapin Logo.. __ $ _ o Computer Science Logo Style, Volume 1$22.95 __ $ _ o Computer Science Logo Style, Volume 2$21.95 __ $ _ o Computer Science Logo Style, Volume 3 (temporarily out of print) o Computer Science Logo Style Disk $.9.95 0 LCSI Logo II 0 Mac Logo 0 IBM Logo $ _ o Approaching Precalculus Mathematics Discretely$47.50(HB) $29.95(PB) $ _ o Phantom Fish Tank $19.95 0 Apple 5.25 0 Apple 3.5 0 MSDOS 5.25 0 MSDOS 3.5 $ _ o Computer Environments for Children $13.95 __ $ _ o Structure and Interpretation of Computer Programs $55.00 __ $ _ o Simply Scheme: Introducing Computer Science $49.95 __ $ _ o Simply Scheme: Introducing Computer Science Disk $10.000 MSDOS 0 Macintosh __ $ _ o The Children's Machine by Seymour Papert $22.50 __ $ _ o Mindstorms (2nd Edition) by Seymour Papert $13.00 __ $ _ o Headlight Stories $15.00 __ $ _ o Fuzzy Logo $3.50 __ $, _ o Creating a Logo Tool Box $4.00 __ $, _ o Conversations with Logo $4.00 __ $ _ o Easy as 11223 $2.50 __ $, _ o A LogoWriter Ecology Simulation $10.00 __ $ _ o A Full Screen LogoWriter Printshape Procedure $3.50 __ $ _ Tax deductible contribution to the Logo Foundation $ _ Total $ _ Please enclose payment or a school purchase order. Name Overseas shipments require additional charges. Please Organization inquire before ordering as the amount depends upon Address destination and carrier.

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Logosium (Logo Symposium) Sunday, June 12, 1994

Sponsored by ISTE's SIG-Logo and the Logo Foundation Hosted by the MIT Media Lab A one day pre-conference at NECC '94, Boston

Mini hands-on sessions Jitterbug Logo Style - it's procedural!

Students, student projects, and video tapes

Time to schmooz with Logo users from around the world

Interactive, informal group discussions on Logo topics - assessment, NCTM standards, action research, new environments, beginning and advanced topics For Registration Information Contact: NECC '94 Office, Lesley College 29 Everett Street • Cambridge, MA 02138 Phone: (617)349-8965 • Fax: (617)349-8968 Internet: [email protected]

Lo o Foundation 250 West 57th Street • New York, NY 10107-2603 Nonprofit Org. U.S. Postage PAID New York, NY Permit #6378