Andrew decorated 20 biscuits to take to a party. He lined them up and put icing on every second biscuit and different decorations on other biscuits. How many biscuits weren't decorated?

There are three versions of this challenge. The idea is to change the colour of all the spots on the grid. Can you do it in fewer throws of the dice?

Can you each work out the number on your card? What do you notice? How could you sort the cards?

This activity is best done with a whole class or in a large group. Can you match the cards? What happens when you add pairs of the numbers together?

Use these head, body and leg pieces to make Robot Monsters which are different heights.

How would you create the largest possible two-digit even number from the digit I've given you and one of your choice?

This investigates one particular property of number by looking closely at an example of adding two odd numbers together.

Can you work out the domino pieces which would go in the middle in each case to complete the pattern of these eight sets of 3 dominoes?

Kimie and Sebastian were making sticks from interlocking cubes and lining them up. Can they make their lines the same length? Can they make any other lines?

This problem challenges you to find out how many odd numbers there are between pairs of numbers. Can you find a pair of numbers that has four odds between them?

Choose four of the numbers from 1 to 9 to put in the squares so that the differences between joined squares are odd.

If there are 3 squares in the ring, can you place three different numbers in them so that their differences are odd? Try with different numbers of squares around the ring. What do you notice?

This problem looks at how one example of your choice can show something about the general structure of multiplication.

An activity centred around observations of dots and how we visualise number arrangement patterns.

Dotty Six is a simple dice game that you can adapt in many ways.