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We've designed this workshop from the ground up to be a stress-free experience for educators and parents. No prior coding experience or technical knowledge is required, and aside from creating user accounts, no advance preparation is needed.



In order to save game files, you and each of your learners will need to create a Scratch account. You can choose to let your students create their own account, or create an educator account that allows you to create bulk accounts and gather students in a virtual classroom. You can sign up for an educator account here. There’s also an offline version of Scratch that doesn’t require an Internet connection or a user account.


Regardless of which option you choose, the setup process is fairly straightforward, and no personal information about children will be collected. Each user account must be connected to an email address.

A Scratch educator account allows teachers to set up logins on behalf of their class, and makes it easier to manage and monitor your group's work. This video by MIT's Scratch team explains how they work.



Kids who engage with this material will be very proud of the fun little tweaks and customizations they add to their project. We encourage you to celebrate their initiative by sharing their work in a Studio, a shared folder where the entire class can see it. This will also make it easier to display their work on your classroom projector or, if teaching remotely, on your shared screen.


Once you've set up your classroom studio, prompt your students to create a blank Scratch file and save their work into the studio. This video, which you can show to your class, explains the process.

This short video describes how to set up a studio in Scratch.

Once you've created a Cat & Mouse Studio, your students will need to create a blank Scratch project and save it there. Show them this clip, which is also available on the Videos page.

Students will be watching and building along with Mr. Tomec as he walks them through the process of creating a game in Scratch, explaining concepts and providing valuable tips along the way.  The lesson clocks in at 75 minutes, and is chunked into 10 different chapters. Each chapter concludes with a “checkpoint” that that will allow learners to catch up if they’ve fallen behind. Each checkpoint includes a visual summary of all the code added during that segment, and a clear goal that must be accomplished before learners move on to the next video.


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Our handy PDF Code Reference summarizes all the code covered in each lesson, and provides other helpful tips gleaned from scores of sessions teaching this material.

SCHEDULING CONSIDERATIONS: Different classes will move through this material at different speeds, but based on our experience, we recommend you allocate a minimum of 150 minutes of instructional time, which will probably mean spreading the workshop over multiple sessions. Students can also be assigned to work on the lessons at their own pace, making this project an ideal fit for asynchronous learning during the COVID era.

LAPTOPS OPEN OR CLOSED? Learners are encouraged, where feasible, to keep their computers open during the lesson and experiment with the blocks, graphics and sound effects while Mr. T is demonstrating them. A few will inevitably fall behind because they’ve been distracted, but checkpoints present a built-in opportunity for teachers to monitor student progress and redirect those who are having difficulty following the lesson.

AVOIDING 'RABBIT HOLES': There will be many opportunities for participants to customize the project and put their own spin on it while they code, but it’s important that everyone follow along with the planned lesson, as the concepts presented build on each other. Learners who veer too far from the lesson plan are likely to get lost and fall down coding rabbit holes that will slow the rest of the class down while they seek supplementary coaching and troubleshooting help that’s outside the scope of the lesson.

ASKING FOR HELP: Students who miss a step or misunderstand an instruction during the lesson should be encouraged to hold onto their questions until the Checkpoint phase at the end of the video. Often, students will discover that Mr. T has anticipated these questions, and that the answer will become plain if they sit with their discomfort for a few seconds and persevere through the lesson. After the clip is over, feel free to rewind and review the material. If an unanticipated problem arises, show the student's work on the projector and invite peers to help sort out the issue. 

ACCIDENTAL DELETION: Participants, particularly those working with touch screens, will occasionally delete large chunks of their project, sending teachers or fellow students scrambling to help them reconstruct lost work. Note that Scratch’s support for “undo” commands and autosaving is limited, and in most cases deleted code blocks are lost forever. Rather than rebuilding lost work, students who lose their projects or fall too far behind should be encouraged to abandon their version of the project and load a “catch-up file”, a pre-made Scratch project that contains all the code blocks the class has assembled up to that point. Along with the link in this paragraph, we’ve included a link to the catchup files (one for every chapter) at the top of our Videos page.

By the end of the lesson, students should have a fully functional video game in hand. Many of your students will have picked new graphics, sound effects, backgrounds, code tweaks and other customizations that put a different spin on the game. This is an opportunity for students to compare notes and inspire each other. You might want to show a few of the more unique projects on the classroom projector, offering feedback and asking questions as you do.



Ontario's new coding curriculum directs students to "read and alter existing code", a goal which can be introduced and accomplished by directing students to "remix" a peer's version. Simply ask them to open the Cat & Mouse studio, select a peer's project and modify it to tweak settings or change  the graphics or sound effects. Right-clicking in the coding area calls up a menu that allows students to create sticky-note comments that explain how they modified the code. Clicking the Remix button at the top of the project saves the modified game as a unique file and automatically credits the originating student.


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You can encourage students to read and alter code by asking them to remix  projects made by peers, adding sticky note comments to specify what they changed. (Click to expand image)

You can further extend this project by challenging learners to apply their new coding skills to new rules and features to Cat & Mouse, transforming the game into something that’s uniquely their own. There's no end to the list of twists and customizations your students might attempt, but some examples include adding new opponents, multiple levels, power-ups, or an introductory splash screen. You’ll find more remix ideas on our remix page, at


Please encourage students who’ve made truly unique remixes to share them with Chromeworks so we can showcase them on our weekly YouTube live stream, the Chromeworks Club. You'll find detailed instructions on sharing files with us on the Remix page.



Students can "remix" each other's work, or their own,  to make a totally different game.

Ask your students to go home and teach the lesson to their parents, grandparents, siblings, cousins or neighbors. Kids who finish this tutorial will invariably be very proud of their new game, and will want to share it with others. Take the project a step further, and supercharge the lesson with a dose of higher-order thinking by encouraging your learners to show the video to others and help them construct their own game under your student's supervision.


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