Create a hand-washing timer Cubelets!

This entry was posted in Education & Robotics on by Alice Pieuchot.

What are you going to do in this activity?

In this activity, you will build a system that will help you to wash your hands properly! Washing your hands properly helps to avoid catching and spreading germs and diseases (and also it smells good!).

A good hand wash lasts 20 seconds!

How to wash your hands properly with Cubelets

What do you need?

  • Age range: 10-13 years old
  • Difficulty:Difficulty level of the activity: Easy
  • Duration: 60 minutes
  • Hardware:
  • Cubelets
  • Lego bricks to stabilize and give a nice look to your robot! (optional)

Right now, with the coronavirus, it is even more important to wash your hands well and often! The robot you are going to build will be able to detect when you start washing your hands and will tell you when it’s time to stop (after 20 seconds). This little robot will help you and your family not being ill!

get rid of viruses


Step 1

Every time an engineer builds a robot, he starts by asking himself the following questions:

  • What’s my robot for?
  • Can I split its mission into several tasks?
  • What are these tasks?

Now, it’s your turn to ask those questions about your hand washing robot! On a piece of paper, write down your answers to the 3 questions above.

Nothing prevents you from getting help from a member of your family, think about this first step together!

Notebook for robotic activities

Answers for Step 1:

  • Detect when you start washing your hands
  • Starts a timer that will last 20 seconds
  • Let you know when the 20 seconds are up

Step 2

Now that you have a better idea of what your robot is going to do, you’ll need to write down even more details about how your machine works.

Below are some exemples, but it’s up to you to find more. Try to find at least 3!

How will it start? Where should it be installed so that it doesn’t get damaged?

Answers for Step 2:

  • How will the robot be able to warn you that the 20 seconds are up? (with an alarm, with a flashing light, by moving?)
  • How will the robot see your hands?
  • How do we make sure it doesn’t fall down?
  • What if someone comes to wash their hands right afterwards?

Step 3

All the questions you’ve asked yourself and the answers you’ve found will help you in this step: choose the Cubelets you need for your robot!

If this is the first time you are playing with Cubelets, we recommend that you first read this Cubelet Getting Started Guide, which will help you get familiar with Cubelets. You will also learn how to make them work together.

We recommend that you make a first selection of Cubelets for a first test. If your robot doesn’t work as you wish, you can always make some changes, and continue your experiments until you are satisfied with your robot!

Answers for Step 3:

There is not one correct answer here. Different robots, composed of different Cubelets, will be able to complete the hand washing mission!

Here is an example of selecting Cubelets to build this robot:

The Cubelets Curiosity Set contains the above Cubelets. You can also choose the Cubelets Discovery Set, you will only need the Rotate Cubelet, which is not required here.

Assembly of the cubelets for the Generation robots tutorial

Assemble your Cubelets and test your robot. Does it react the way you want? Does anything need to be modified?

Step 4

Right now, your robot detects your hands getting closer, and starts its motor and light as soon as it spots them. That’s good, but it’s not quite what we want./

In order for our robot to perform its mission properly, it must behave as follows:

  • Spot you
  • Wait 20 seconds
  • Turn on its motor and its light

You’re the one who’s going to code this behaviour in the Cubelets Blockly application.

Here’s what you’re going to code:

IF Proximity Cubelet detects something approaching

THEN the timer starts for 20 seconds

OTHERWISE, nothing happens

Answers for Step 4 :

Step 5

Your robot’s almost ready! All you have to do is stabilize it, give it a design you like with some Lego bricks and find a nice spot so it can complete its mission!


Put the robot where it can detect your hands when you wash them.

Do not put the robot too close to the sink, water and Cubelets do not mix well!