Double Spinners

'Create your own spinners and compare the results you expect with what you actually get.’

What is random?  How can we be sure that when we spin a spinner we do it randomly?  How can we predict events that are random? You should consider and answer these questions and many more during this activity.  Here you are encouraged to create and program your own virtual spinner that should behave randomly.  You will test it out and share results with your classmates.  Can you predict the results of the spinner from what you know about probability?  If you carry out the experiment  more and more times what is likely to happen to your results?

The following slideshow should give teachers an idea what this activity entails:


Here is the associated worksheet  Comparing Theory with Experimental Data.

A partially complete scratch file is provided here  double spinner.

An online version of Scratch can be used from here (no download needed)

A short help video for using scratch is provided below.

Alternatively, if you are not creating the spinners you can use the Scratch Spinners applet below.

The teacher can collect all the individual students’ results in this ready prepared spreadsheet  spinner collection.

Scratch Help Video

Here is a short video to show how to move the scripts around to create the spinners in scratch:

Scratch Spinners

If you are not creating the scratch file for yourself you may wish to use the following applet that simulates the two spinners.  Click on the arrows to make them spin.


Here follows an outline of what the task is. 

  • Students should consider what all the possible outcomes are from spinning these two spinners and adding the results.

  • Students should download scratch if not already installed on their computers.
  • The scripts will need to be correctly ordered to create two different spinners.
  • Experimental data should be collected and compared to predictions.
  • Data could be shared with the whole group so that a group discussion of what happens to experimental probability as the number of times an experiment is carried out increases.  A ready made spreadsheet with pre-programmed graphs is available to help with this.
  • Other experiments could be compared – finding the difference of the spinners instead of the sum and creating biased spinners.
All materials on this website are for the exclusive use of teachers and students at subscribing schools for the period of their subscription. Any unauthorised copying or posting of materials on other websites is an infringement of our copyright and could result in your account being blocked and legal action being taken against you.