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Use scratch to make a usable tool

Use Scratch to design and code a useful digital calculator or timer. Test buttons, fix bugs, and create a working tool to reuse.

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Step-by-step guide to use Scratch to build a digital calculator or timer

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Scratch Tutorial | Programming for Kids and Beginners

What you need

Scratch account, paper, pencil

Step 1

Open scratch.mit.edu and click "Create" to start a new Scratch project so you have a blank slate to work on.

Step 2

Decide whether you will build a calculator or a timer and say your choice out loud so your project has a clear goal.

Step 3

Write three features you want your tool to have on your paper so you know what to build first.

Step 4

Draw a simple layout on your paper showing where the display and buttons will go so you have a plan to follow.

Step 5

In Scratch make a new sprite and name it "Display" so you have a place to show numbers or time.

Step 6

In Scratch create variables named DisplayText FirstNumber and Operator for all sprites so your code can remember numbers and the operation.

Step 7

Make one number button sprite and add code so when that sprite is clicked it appends its digit to DisplayText (if DisplayText is "0" then set it to the digit) so numbers appear on the display.

Step 8

Create digit buttons 0 through 9 by copying the number button and changing each label so you have every number to press.

Step 9

Make operator buttons (+ - × ÷ or Start Stop for a timer) and add code so each operator button saves DisplayText into FirstNumber sets Operator and resets DisplayText to "0" so the tool knows what to do next.

Step 10

Create an equals button and add code that checks Operator then calculates FirstNumber (operator) DisplayText and sets DisplayText to the result so your calculator gives answers.

Step 11

Add a clear button and add code to set DisplayText to "0" and clear FirstNumber and Operator so you can start fresh anytime.

Step 12

Test your tool by trying at least three different calculations or timing runs so you can see how it works in action.

Step 13

Fix any bugs you find by editing the scripts then test again so your tool becomes reliable and reusable.

Step 14

Save your Scratch project and write short usage instructions in the project notes so other people know how to use it.

Step 15

Share your finished creation on DIY.org so other kids can see and try your useful tool.

Final steps

You're almost there! Complete all the steps, bring your creation to life, post it, and conquer the challenge!

Complete & Share

Help!?

What can we use if we can't access scratch.mit.edu or a computer to do this project?

Use Scratch Desktop or the Scratch app (or ScratchJr for younger children) to open Create and follow the same steps to add a Display sprite, the DisplayText/FirstNumber/Operator variables, and number/operator buttons.

My number buttons don't change the display—what should I check?

Make sure you created the variables DisplayText, FirstNumber, and Operator 'for all sprites' and that each number button's click script follows the step that sets DisplayText to the digit when DisplayText is "0" or appends the digit otherwise so the Display sprite updates correctly.

How can I adapt the activity for different ages?

For younger kids, simplify by drawing a very basic layout and using a single Display sprite with only a few copied number buttons as in the 'Make one number button' step, while older kids can add decimals, memory variables, and expand the equals button code to handle chained operations.

How can we enhance or personalize the finished tool?

Follow your 'Write three features' planning step to add color themes, button sounds, a Start/Stop operator for timer mode or a toggle to switch modes, then update the project notes and share on DIY.org.

Watch videos on how to use Scratch to build a digital calculator or timer

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How to use Scratch for Kids! | Coding for Kids | STEM MC

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Facts about Scratch programming for kids

🐱 Scratch's mascot is the Scratch Cat — the platform was created at MIT to help kids learn coding by making games and stories.

🔢 The first mechanical calculator, the Pascaline, was invented by Blaise Pascal in the 17th century to help with arithmetic.

⏱️ Digital timers and stopwatches often measure time in milliseconds, letting us time things super precisely for games and experiments.

🐞 The term “bug” for a software error became famous after a real moth was found in a 1947 computer — and the story still bugs programmers in a fun way!

🧠 Studies show block-based tools like Scratch help kids build problem-solving skills, logic, and creativity while they learn to code.

How do I use Scratch to create a simple digital calculator or timer?

Start by planning the tool’s features and interface. In Scratch, create sprites for buttons and a display, then make variables for numbers and results or time. Use events (when this sprite clicked) to update variables and run operator blocks for calculations or timer loops for countdowns. Add custom blocks for repeated logic, test each button, fix bugs, and save or share the project so the tool can be reused.

What materials and tools do I need to build a calculator or timer in Scratch?

You need a computer or tablet with internet and a modern browser (or the offline Scratch app), and a Scratch account for saving projects. Optional: mouse for easier clicking, headset for voice prompts, notebook and pencil for planning, and reference materials like Scratch tutorials. For classroom or group use, have a projector or tablet per student and an adult to help with debugging and account setup.

What ages is making a calculator or timer in Scratch suitable for?

Scratch projects are generally suitable for children aged about 8–16. Younger kids (6–7) can participate with adult guidance, especially for planning and testing. For complex calculators or timers, ages 10+ are comfortable handling variables, operators, and custom blocks independently. Ensure reading and basic typing skills; adapt features and supervision level to a child’s experience. Group teaching boosts learning for beginners.

What are the benefits of having my child build a calculator or timer in Scratch?

Building a calculator or timer in Scratch teaches computational thinking, logical sequencing, and debugging skills. Kids practice math concepts while designing user interfaces and managing variables. Testing and fixing buttons builds perseverance and attention to detail. Reusing the finished tool reinforces pride and practical value. It’s also a gentle introduction to programming concepts like loops, conditionals, and events, which prepares children for more advanced coding.

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