These squares have been made from Cuisenaire rods. Can you describe the pattern? What would the next square look like?
Cut differently-sized square corners from a square piece of paper to make boxes without lids. Do they all have the same volume?
Can you use this information to work out Charlie's house number?
Think of a number. Square it. Subtract your starting number.
Is the number you're left with odd or even?
Try with other numbers.
What do you notice?
How do these images help you explain your observations?