Say: “We’re going to see how many shapes we can find”
Draw: One of the grids below.
Starter
“How many squares?”
Main
“How many squares now?”
Dessert
“How many rectangles?”
Tips for grown-ups
Nearly everyone says 4 for the Starter (grown-ups too). Rather than correcting, try starting to trace the outside edge with your finger and saying “Hmm, I wonder….”
Counting the same square twice can be an issue. Try encouraging them to go over each square they find with a different colour.
For Dessert, ask: “What makes something a rectangle?” Answer: four “right” (rect in Latin) angles. For younger kids, you could phrase this as “L” angles. So a square is a rectangle too.
Branch of mathematics
Combinatorics, the maths of counting things carefully. The number of squares in bigger and bigger grids goes 1, 5, 14, 30, and so on: the “square pyramid” numbers.
Answers
Starter: 5 (4 little squares and 1 big one)
Main: 14 (9 little squares, 4 medium ones and 1 big one)
Dessert: 36. A square is a special kind of rectangle (one whose sides are all the same length), so the 14 squares from Main count too. The other 22 are: 12 that are 1 box by 2, 6 that are 1 box by 3, and 4 that are 2 boxes by 3
How did it go at your table? Let us know in the comments!