Layers in the Sand An original lesson plan developed by Erin Cziraki.
This activity is intended to be presented after students have been introduced to the concept of average speed (velocity), the formula used for finding average speed, the variables involved, and the appropriate metric units. For example, if a teacher typically spends a week on the subject of velocity, this activity would fit in well on days two or three. The activity challenges students to measure the velocity of different sized grains of sediment falling through water. The students then use their findings to answer a question regarding the layering of different sediment sizes.
Level of Inquiry: 2 Scientific Process Skills: observing, measuring, communicating, defining operationally, investigating
A. South Carolina State Standard: 8-5.2: Use the formula for average speed, v=d/t, to solve real world problems.
B. Performance Objectives: Upon completion of this activity, students will successfully be able to: a. Recall the formula for average speed b. Identify the variables involved c. Recognize and identify appropriate metric units for representing average speed d. Use the formula to solve real-world problems
C. Body: 1. Concept Exploration Hook: A brief (around 3 minute) video is played showing footage of Hurricane Katrina’s storm surge as it arrived in Mississippi (this is posted along with the lesson plan). An imaginary friend of the teacher’s happens to live in the area. The friend’s yard had been completely covered in water when the storm surge came crashing in and as the storm moved away, the water became still for a few days before receding, leaving piles of debris and sand behind. While cleaning up the piles of sand from her beachfront yard, the friend discovered that the sediment had settled in defined layers. The friend collected a small sample and sent it to the teacher asking why the sand had done this. A close-up picture of the layered sample is shown on the projector and the students are asked to jot down their observations about the sample (also posted with lesson plan). They are then asked to provide a possible explanation for what they observe (see Activity packet). If available, the teacher can also show a settling tube that has been shaken up so the students can see how the different sizes separate.
Activity: The teacher explains that he/she has devised an experiment in order to gather observations and data that may help answer this question. The teacher thinks the answer may lie in the way the sand settles out from the water once the water has stopped moving. The sample of sand that the friend sent to the teacher has been separated out by size and the students will explore how the different sized sand grains fall through the water. The class is divided into groups of four before beginning an activity involving stations. Before the groups move to their first station, they work together to answer some review questions involving average speed (see Activity packet). Once the groups have had time to answer the questions, they move to their first assigned station to begin the activity (see Activity Packet for methods). While the groups are working, the teacher wanders among the stations asking and answering questions and offering guidance and suggestions. The teacher will also check to make sure that the groups have correctly answered the pre-activity questions and ask the students to explain how to find the mean of a group of numbers. Materials: Tall plastic cups- to drop sand in Clear 2-liter bottles with neck removed- to drop pebbles in Samples of sand of three different sizes Small pebbles Medium sand (this can be collected from the swash zone of the beach) Fine sand (this can be collected from the dunes on the beach) ***make sure all sand is DRY for this activity so it doesn’t stick together*** Timers or stop watches Metric rulers Water
2. Concept Introduction Once all of the groups have completed all of the stations, the teacher asks one member of each group to record each of their mean velocities on the class data table written on the board. If the teacher notices any major differences in the groups’ data, the teacher will ask for possible reasons for why the groups found different velocities (possible reasons could include operation problems with the stopwatch, the “watcher” and “timer” not responding quickly enough, distance measurements being taken in inches instead of centimeters, etc.). The teacher then reviews the answers to the pre-activity questions as well as the correct way to find average velocity, the correct units to use, and the correct way for finding the mean velocity for each station. The students are then asked to correct any mistakes they made on their papers. 3. Concept Application After the teacher completes the Concept Introduction, the students are then asked again why they think the sand in the sample ended up in layers on the friend’s yard. The students are asked to relate their answers to the activity they just completed and to reference the data that they collected. If the students were careful while performing the activity, they will see that the larger the size of the sand grain, the faster it falls through the water. They should reach the conclusion that once the hurricane’s tidal surge stopped moving, the larger grains dropped to the friend’s yard faster than the medium grains and that the medium grains dropped faster than the smallest grains resulting in the layers of sand.
D. Review/Evaluation: Once the students are finished answering the Application question, the teachers collects the activity packets. An assessment sheet is then handed out and depending on time, the students either work independently to finish the sheet before leaving class or are asked to complete it at home and return it the next day (see Challenge Questions). The students’ performance will be assessed according to the grading rubric and the teacher can then determine if the objectives for this activity have been met.
Teacher notes: This activity will probably take more than one 75-minute class period but shouldn’t take two. Give the students just a small amount of sediment sample to work with so that they don’t just dump the whole thing into the cup of water. They should add the sediment just a small pinch at a time so they can accurately measure the velocity of one or a few grains falling at one time. Layers in the Sand: Activity
As you saw in the video, waves produced by hurricanes can be very powerful and destructive. They can pick up and carry lots of debris including sand and carry is for long distances. A friend of mine was living in Mississippi when Hurricane Katrina made landfall. She owns a very nice beach-house that was only slightly damaged by the storm. Her yard was a different story though. When the big storm surge came in, it flooded her yard and stayed flooded for days. Slowly the water dropped and she found that piles of sand were left behind. As she was working to remove all the sand and put it back on the beach, she noticed that there were three different layers in the sediment. She took a sample and sent it to me and asked me why this had happened.
1. The picture on the projector is a close-up shot of the sample that I received. What are some things that you notice about the sand and the layers?
2. What do you think is a possible explanation for what you see in the sample? Once you are in your groups, work together to answer the following questions. Even though you are working together, everyone needs to write down their answers.
3. What is the formula for average velocity (speed)?
4. What does each of the variables in the formula stand for?
5. What are some examples of metric units that a scientist would use when working with this formula?
After you finish answering these questions, you need to assign each member of your group to a job. The four jobs are: a. Timer b. Recorder c. Watcher d. Dropper Once everyone has a job, read the instructions below.
The sample that my friend sent to me was actually quite large and I was able to use some of it in this experiment. She mentioned that she saw three layers so I separated the grains into three different groups based on their size. Your group will be moving around to three different stations and at each one you will be investigating how the different sizes fall through the water. At each station: a. The Dropper will drop some of the sediment into the water. b. The Watcher will say “start” when the first grain passes the first mark on the cup and “stop” when the first grain passes the last mark on the cup. c. The Timer will start and stop the stop-watch when the Watcher says to. d. The Watcher will use the ruler to measure the distance between the two marks on the cup. You will have two measurement units to choose from on the ruler. Be sure to use the units that a scientist would use! e. The Recorder will write down all of the data for the group in the data tables.
Below, you will find the data tables as well as some hints that might make this activity a little easier. Station 1: Fine Sand Hints: 1. Practice a couple of times first so that everyone knows what to do. 2. Have the Dropper take just a pinch of sand and sprinkle it into the cup. 3. Hold a piece of white paper behind the cup so the Watcher can see the sand more easily. 4. Have the Watcher lean down so that the container of water is at eye-level. 5. Be sure to record your units in the data table for all of the variables.
Data: Trial Distance Time Velocity
1
2
3
Use this space to show your work for calculating velocity.
Calculate the mean velocity for the fine sand. Show your work below and don’t forget your units!
Mean velocity for fine sand: Station 2: Medium Sand Hints: 1. Practice a couple of times first so that everyone knows what to do. 2. Have the Dropper take just a pinch of sand and sprinkle it into the cup. 3. Hold a piece of white paper behind the cup so the Watcher can see the sand more easily. 4. Have the Watcher lean down so that the container of water is at eye-level. 5. Be sure to record your units in the data table for all of the variables.
Data: Trial Distance Time Velocity
1
2
3
Use this space to show your work for calculating velocity.
Calculate the mean velocity for the medium sand. Show your work below and don’t forget your units!
Mean velocity for medium sand: Station 3: Pebbles Hints: 1. Practice a couple of times first so that everyone knows what to do. 2. Have the Dropper choose smaller pebbles to drop into the cup. 3. Drop only one pebble at a time and start with the pebble just touching the surface of the water. 4. Have the Watcher lean down so that the container of water is at eye-level. 5. Be sure to record your units in the data table for all of the variables.
Data: Trial Distance Time Velocity
1
2
3
Use this space to show your work for calculating velocity.
Calculate the mean velocity for the pebbles. Show your work below and don’t forget your units!
Mean velocity for pebbles: Summary Data Table: Grain Size Average Velocity
Fine Sand
Medium Sand
Pebble
After your group has finished all three stations, make sure that everyone copies the data from the Recorder into your own packet. Then send one person from your group to the board to share the results that your group found.
Stop here and wait for the rest of the class.
Now that you have completed this experiment, why do you think that the sand ended up in layers on my friend’s lawn? In your answer be sure to reference the data that you just collected. Challenge Questions
One morning you are ridding in the car with your mom on the highway and you are telling her about the exciting things you have been learning about velocity. You then pass a speed limit sign that says “65 miles/hour” and you explain that scientists use different units when measuring velocity.
1. What are at least 3 examples of the units that a scientist would put on a speed limit sign?
Your mom then challenges you to estimate how fast she is driving. You pull out a piece of paper from your bag and a calculator. You tell your mom that when you say “go” she should start paying attention to how far she has driven. You and your mom then ride along for half an hour before you say “stop” and ask how far she had gone. She tells you that the car has travelled 38 miles.
2. What formula could you use in order to determine how fast your mom was driving?
3. What does each of the variables in the formula stand for?
4. According to your formula, how fast was your mom driving (don’t forget your units)? Is this too fast or too slow according to the speed limit sign? Grading Rubric
0 points 1 point 2 points 3 points Changes made to answers in activity No changes Few changes Some changes Student corrected packet during review made made made most or all of his/her session mistakes
Answer to final Question answered Question answered and Question answered in question in activity Question not but answer does not answer makes sense a clear and understand- answered logically relate to the but is not related to able way. Answer question or answer is data collected during refers to data collected not comprehendible activity in an effective manner
Challenge question Question not Only one example Only two examples At least three examples #1 answered given; many of the units given; some of the units given; most or all units not metric not metric are metric
Challenge question Formula given uses Formula given uses #2 Question not Incorrect formula given correct variables but correct variables and answered variables are not in variables are in correct correct place place
Challenge question Question not Most variables One variable All variables defined #3 answered defined incorrectly defined incorrectly correctly
Challenge question Question answered Question answered Question answered #4 Question not but did not use formula; using formula but correctly using formula answered incorrect answer and either answer is incorrect and correct units incorrect units or incorrect units used provided