Introducing algebra

problem
Cat food

Age

7 to 11

Challenge level

Sam sets up displays of cat food in his shop in triangular stacks. If Felix buys some, then how can Sam arrange the remaining cans in triangular stacks?
problem
Doplication

Age

7 to 11

Challenge level

We can arrange dots in a similar way to the 5 on a dice and they usually sit quite well into a rectangular shape. How many altogether in this 3 by 5? What happens for other sizes?
problem
Counting counters

Age

7 to 11

Challenge level

Take a counter and surround it by a ring of other counters that MUST touch two others. How many are needed?
problem
Price match

Age

7 to 11

Challenge level

Can you find pairs of differently sized windows that cost the same?