Conjecturing and generalising

Players take it in turns to choose a dot on the grid. The winner is the first to have four dots that can be joined to form a parallelogram.

Players take it in turns to choose a dot on the grid. The winner is the first to have four dots that can be joined to form a parallelogram.

Imagine we have four bags containing numbers from a sequence. What numbers can we make now?

Try out this number trick. What happens with different starting numbers? What do you notice?

Here is a selection of different shapes. Can you work out which ones are triangles, and why?