Squares can be made in two distinct ways using Polydron, as
the picture shows.
How much bigger is the one made from $4$ right angled isosceles triangles?
Squares can easily be clicked together to make other shapes.
A pentomino is a shape made from $5$ squares joined together along a common edge. Can you find all $12$ distinct pentominoes? Do all your pentominoes have the same perimeter length?
How many pentominoes have line symmetry? Rotational symmetry?
How many of the pentominoes will fold up and clip together to make 'lid-less' boxes? Why not discuss first which will fold up and which won't, before trying to fold them?