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Build an AI Exercise Timer You Can Wear

Train a micro:bit to tell exercising from standing still, then wear it. Button A shows active seconds. Button B shows still seconds.

Ages 7+ (this site: 6–9 and 10–12)The project page does not give a total time. It includes a 30-second check.CreateAI is free with no login. The micro:bit, cable, and batteries are extra. No price is listed.Robots & MakingEnds in a real thing: A micro:bit you can wearMedium

At a glance

Age7 and up, from CreateAI. On this site that is the 6–9 and 10–12 bands, with you there under 13.
TimeNot stated, except a 30-second accuracy check.
CostSoftware: free, no account. Hardware: a micro:bit V2 and 2 AAA batteries. Price not listed.
CategoryRobots & Making
You'll end withA wearable timer

This is a timer that learns what “moving” looks like for the person wearing it. The official project trains two actions, exercising and not exercising, then counts seconds on the micro:bit. It is not a chatbot. The data stays on the device.

Tools (and their age limits)

ToolWhat it’s for hereAccount age / who logs inFree?
micro:bit V2The board you wear. It senses movement.No account on the board. CreateAI says the lessons suit children from age 7. You handle the USB cable and the battery pack.You need the board. The project page does not list a shop or a price.
CreateAICollect samples and train the modelNo login. CreateAI says it stores no personal data and does not share student data with a cloud service. Models run on your device.Free, from the CreateAI page.
MakeCodeThe timer program. Open it from the CreateAI project.The exercise-timer page sends you to MakeCode with the project. It does not ask for an account in the steps we read.Described with the same free project. We did not find a separate price.

Who does what

Kid does

  • Picks safe moves: marching, jumping jacks, or walking, as the project suggests
  • Wears the board and records samples, with you watching the cable
  • Stands still, in more than one direction, for the “not exercising” samples
  • Presses A and B to read the seconds

Parent does

  • Opens CreateAI in Chrome or Edge, or the tablet app the page mentions
  • Connects the board and clicks Train
  • Downloads the program and plugs in the battery pack
  • Decides the strap is comfortable and not too tight

Materials

From the project page:

  • A micro:bit V2, a USB data cable, and a battery pack with 2 AAA batteries
  • A computer with Chrome or Edge, or a CreateAI app on an iPad or Android tablet
  • A second micro:bit V2 only if the computer has no Bluetooth
  • A strap, a holder, or a craft stem or elastic band to hold it on a wrist
Not needed: a name, an email, or an account. Don’t label the samples with one.

Steps

  1. Parent Open the project on the micro:bit site and then in CreateAI. The page says some sample data is already there for exercising and not exercising. You still add your own.
  2. Parent Connect the board with the Connect button and follow the on-screen steps.
  3. Together Strap it on a wrist loosely enough to be comfortable. Record “exercising” while your child does a move you both agreed is safe. Button B on the micro:bit can start a recording. Delete a bad sample.
  4. Kid Record “not exercising” while holding still, facing different ways. The page asks you to check that moving samples look like movement and still samples look still.
  5. Parent Train, then test. Move and see if it estimates exercising. Hold still and see if it estimates not exercising. Let someone else wear it. The page says more data usually helps.
  6. Parent Edit in MakeCode and download onto the board. You can leave the code as it is. Unplug the USB cable, add the battery pack, and wear it.
  7. Kid Press A for seconds spent exercising and B for seconds spent still. Reset with the reset button on the back, or by reconnecting the battery.
  8. Together Check the timer: reset, exercise for 30 seconds, press A. The page says you should see a number close to 30. If not, add samples and train again.

Copy-paste prompts

You do not need a chatbot for the build. This one only helps you pick living-room moves.

What to record

Plan the movement samples

I'm a parent doing the micro:bit CreateAI "Simple AI exercise timer" with my child, who is [AGE]. The project already has two actions: exercising and not exercising. Please suggest three exercising moves that are safe in our living room (no equipment) and three ways to stand still for the "not exercising" samples, including different directions the board might face. Do not change the project into a different timer. No names or locations.

What you’ll end up with

A micro:bit that shows an icon while it thinks you are exercising or still, and a number of seconds when you press A or B.

Placeholder

No photo yet. A picture of the board on a wrist, with no face, will go here after a real test.

Safety box

  • Age: CreateAI says age 7 and up. Under 13, you are there the whole time. This is not a chatbot. Safety & Ages hub
  • No personal info. CreateAI says it does not collect or share personal data. Don’t type a name into a filename you later upload somewhere else.
  • Bodies: stop if a strap pinches, or if a move hurts. The page’s examples are marching, star jumps, and walking. Star jumps need space.
  • Batteries and the cable are yours to connect. The small board is not a toy for under 3. The page does not print that warning. It is ordinary hardware sense.
  • The model can be wrong. The page asks whether it works as well on another person. Test that before you trust the number.
  • Bluetooth: if your computer has none, the page says you need a second micro:bit V2. We are not skipping that.

Age adaptations

AgeHow it worksTips
6–9They move. You click. CreateAI’s floor is 7, so a 6-year-old is younger than the page suggests.One move only. You record. They press A and B.
10–12Side by side. They can decide which sample looks wrong.Compare it with the non-ML step counter the project page links, and ask when the learning is actually useful.

Variations & next projects

  • The page’s own extensions: a “?” when the model is unsure, or a sound when exercising starts. Do those in MakeCode after the timer works.
  • Clap, wave, and jump are examples on the CreateAI overview, not the labels in this project. You could collect those as a different model later. This page does not swap them in.
  • No board yet: do not buy from a link we did not check. The project page does not name a shop.

Source & inspiration

The exercising and not-exercising samples, the Train model button, the 30-second check, buttons A and B, and the parts list come from the micro:bit “Simple AI exercise timer” project page. CreateAI's own page says the tool is free, has no login, keeps models on your device, collects no personal data, and is meant from age 7. It also says students can train movements like a clap, a wave, or a jump. Those are examples of what CreateAI can learn. They are not the two labels in the exercise-timer project. This guide follows the exercise timer. The wording is ours.

Inspired by:

Facts checked against:

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