contributed articles DOI:10.1145/3368856 Embracing a constructionist ap- A codable computer half the size of a credit proach to computing education,11 the micro:bit has moved from a local edu- card is inspiring students worldwide to develop cational experiment in the U.K. to a core computing skills in fun and creative ways. global effort driven by the Micro:bit Educational Foundation (microbit. BY JONNY AUSTIN, HOWARD BAKER, THOMAS BALL, org), a nonprofit organization estab- JAMES DEVINE, JOE FINNEY, PELI DE HALLEUX, lished in September 2016. There are STEVE HODGES, MICHAŁ MOSKAL, AND GARETH STOCKDALE now over four million micro:bits in the market in over 60 countries with many hardware, content, and education part- ners participating. The BBC and its partners developed The BBC the micro:bit as an inexpensive, power- ful, and easy-to-use learning tool guid- ed by five major design goals: 1. Have a low barrier to entry. Finan- micro:bit— cial cost and simplicity are important considerations for any technology, but even more so in an educational setting. The micro:bit needed to be affordable, From the U.K. easy to deploy, intuitive to use, simple to program, and integrate well with ex- isting school IT infrastructure. 2. Be fun and creative. The micro:bit itself needed to offer an exciting, to the World engaging, inclusive introduction to coding and making. Inspired by Ar- duino and the Maker movement,7 the project sought to turn teachers and students from digital consumers into digital creators by integrating the micro:bit into their own real-world, physical creations. IN 2015, THE BBC launched the Make It Digital initiative, 3. Have a low floor, high ceiling, aiming to encourage a new era of creativity in the and wide walls. When designing the young using programming and digital technology as micro:bit, providing good educational value to students and teachers was the its medium. Simultaneously, the initiative also would prime consideration. It needed to be support the U.K.’s mandate to teach computer science easy for inexperienced learners to get concepts at all grade levels.13 started (low floor); enable rich learn- ing opportunities that grow with user The micro:bit is a small programmable and expertise, provide progression in both embeddable computer designed, developed, and programming language and applica- tion complexity (high ceiling); and en- deployed by the BBC and 29 project partners to able students to reach the ceiling via approximately 800,000 U.K. Year 7 (11/12-year-old) multiple pathways to embrace a di- school children in 2015–2016. Referring back to its verse audience (wide walls).11,15 4. Open a window into the future. 4 work with the BBC Micro, the BBC described the Computing technology is becoming micro:bit as its “most ambitious education initiative in ever more ubiquitous, connected, and embedded. In the 1980s, the BBC Mi- 30 years, with an ambition to inspire digital creativity cro4 captured the essence of the de- and develop a new generation of tech pioneers.”1 vices that were to come over the next 62 COMMUNICATIONS OF THE ACM | MARCH 2020 | VOL. 63 | NO. 3 Girlsday, hosted by Microsoft, The Netherlands, drew many happy participants. 30 years: the desktop PC. The micro:bit more children coding and to improve from battery power and embedded was designed as a modern-day equiva- digital literacy. Research shows that into children’s projects. There also lent, capturing the connected, embed- physical computing—combining soft- are cost implications for children, ded nature of devices that are to come ware and hardware to build interactive parents, and schools wanting to start for the next 30 years. physical systems that sense and re- making: devices and accessories need 5. Be applicable beyond computer sci- spond to the real world—can engage a to be affordable enough to be accessi- ence. Cross-curricular activities can of- diverse range of students.10 The simul- ble by children and parents from a va- fer diverse and inclusive learning.3,12,16 taneous global interest in the maker riety of backgrounds. This is important when we consider movement also suggests an appealing Engaging, capable, hardware. Fig- the gender disparity in computing to- way to engage children is to incorporate ure 1 shows (a) the front and (b) the day. The micro:bit project aimed to making, creating, and inventing as part back of the micro:bit, which mea- stimulate curiosity about how comput- of the software development process.7,9 sures 4cm x 5cm. Like many “develop- ing can be applied across a variety of However, the BBC observed there ment boards,” the micro:bit is an ex- disciplines, ranging from science and was no prior technology on the market posed printed circuit board with all its technology/engineering to the arts and that suited the complete novice and components visible (in fact, explicitly mathematics (STEAM). that had been designed as an educa- labeled, as a learning opportunity). In this article, we describe the de- tional tool from the outset. For exam- The micro:bit is designed to be engag- sign of the BBC micro:bit and the real- ple, Arduino19 set a new standard in ing and interactive from the start: the ization of these goals, exemplified the field, but requires wiring for virtu- front is designed to resemble a face through a sample set of diverse proj- ally all of its projects as well as the in- with colored streaks of hair (upper left) ects. We review the project’s history as stallation of a custom IDE and device and eyes as the logo (upper middle). it transitioned from a U.K.-centric to a drivers. The Raspberry Pi is a highly This playful design should not be worldwide project, concluding with capable device that runs a full operat- mistaken for a lack of capability. The lessons learned and project outcomes. ing system, but also has a reliance on board is based around a modern 32- additional peripherals to enable phys- bit ARM Cortex-M processor (16kB The BBC micro:bit ical computing. Its associated high RAM; 256kB non-volatile flash) and The BBC spent two years investigat- power consumption and complexity hosts an array of input/output capa- PHOTO COURTESY OF PETER HELDEN, @PETERHELDENS. COURTESY PHOTO ing previous work and new ideas to get also means it cannot be easily run bilities including a 5x5 LED matrix, MARCH 2020 | VOL. 63 | NO. 3 | COMMUNICATIONS OF THE ACM 63 contributed articles Figure 1. The BBC micro:bit. tion via battery power. This allows a student to unplug their micro:bit from a computer and show their creation to a teacher, parent or friend wherever or whenever they want. The solution delivered by the BBC’s partners includes support for Blockly, JavaScript and Python, all via Web apps. Figure 2 shows a screen snapshot of Microsoft’s MakeCode (https://makecode.com) Web app for the micro:bit, which supports pro- gramming via both Blockly and Java- Script. The Web app has five main sec- (a) (b) tions: (A) menu bar with access to front, with two buttons, back, with processor, accelerometer, 5x5 LED display, compass, Bluetooth, projects/examples and switching be- and edge connector (bottom) USB and battery connectors tween Blockly and JavaScript editors. To support progression, the editor also supports conversion of programs Figure 2. The MakeCode Web app for the micro:bit (https://makecode.microbit.org). between Blocky and JavaScript—us- ers can round-trip programs to see their code in visual or text-based rep- resentations; (B) Blockly toolbox of micro:bit API categories, represent- ing the hardware capabilities of the micro:bit. This toolbox can be ex- panded through third-party exten- sions; (C) Blockly programming can- vas showing a simple reactive program. MakeCode enables event- based programming through a light- weight scheduler in the underlying micro:bit runtime; (D) micro:bit sim- ulator for execution of the user’s pro- gram in browser; (E) download but- ton, which invokes an in-browser compiler/linker to produce a binary executable (a “hex file”). The Python solution for the micro:bit is based on MicroPython (https://mi- two programmable buttons, the abili- ented toward a simple and inclusive cropython.org), an implementation of ty to sense motion, gestures, magnet- starting experience with room for pro- Python 3.0 for microcontrollers. It in- ic fields, temperature and light. The gression. In-school trials with a cludes a full Python compiler and run- device also includes a USB interface micro:bit prototype validated the time that executes on the micro:bit and and edge connector with touch sensi- BBC’s approach of using a Web app supports a read-eval-print loop to exe- tive, digital/analog pins that allow ex- based on the popular Blockly frame- cute commands sent via a terminal, for ternal sensors, and actuators to be work8 for students to create scripts via interactive use. This solution also al- connected via crocodile clips or ba- the block-based visual programming lows a Python script to be embedded nana plugs. Finally, the device can paradigm pioneered by Scratch,14 and alongside the compiler/runtime and communicate with phones, tablets, providing a simulator for students to downloaded as a hex file from the Py- and computers via Bluetooth Low En- execute and debug their programs, all thon Web app for the micro:bit (https:// ergy (BLE) or directly with other inside a Web browser. python.microbit.org). micro:bits using a low-level 2.4GHz In addition to block-based visual A low-friction end-to-end experi- radio protocol.