Probability Spinners

The spinner activity can display up to four spinners. These can be used as random number generators in lessons. With the built in activities you can practice BODMAS, algebraic substitution or challenge students to find the rule to produce a result using addition, subtraction, multiplication and division.

Controlling the virtual manipulative

Click the spin button to spin the sliders. You can change the number of spinners shown by clicking the number selector in the top right hand corner. Initially six sided hexagon spinners are shown which are useful to simulate dice. To change the number of sides for the spinners make sure you have selected settings mode and then drag the sliders to new values. The slider max value is 12, but if you click on the number you can enter your own manually, although in practice 50 is about the maximum number that visually fit on the spinner.

Edit mode

In edit mode, you can use the probability spinner however you want. For example to generate random numbers, or probability experiments. In this mode the controls to change the number of sides on each spinner are visible.

Game modes

The game modes use the spinner values, this means that they really require at least two spinners and the challenges are hardest with four spinners. In the game modes your can change the time limit to reflect the difficulty. There is also an option to not allow negative numbers occuring in the calculation, click the control to toggle negatives on or off.

Finding the rule game

The rule guess game is not too dissimilar to the countdown game shown on British TV. First select ‘find rule’ from the select control and press the spin button. When the spinners have stopped you will see a target number in the bottom right of the screen. The aim of the game is to use the operators ×,+,- to reach the number using each spinner value once and once only. Note the number is always attainable and obviously there might be more than one way to get the result. You can see the way the computer calculated the result by clicking the expression above the target number. To view the calculation in algebraic notation click algebraic expression. The first spinner is letter a, second letter b, third c and fourth d.

Calculate Mode

First select ‘calculate’ from the select control followed by spin. When the spinners have stopped a calculation is revealed using their values. The students can work out the answer. To show the answer click the answer.

Substitution Mode

This mode works in a way similar to the calculate mode, but an algebraic expression is shown. The students need to substitute the letters using the spinner values. The completed substitution can be clicked to reveal it, followed by the answer. This is a great way to slowly introduce some algebra with just two spinners, but slowly build up over time to use the four spinner, which can produce more complex expressions.