Here is a hexagon using 6 matchsticks. Move 4 matchsticks to create 2 triangles.
Here we have 2 triangles, with the small one inside the large one.
Can you move 3 matchsticks to have 4 triangles?
Move 4 matchsticks to create 5 triangles, the triangles don't have to be equal in size.
Move 6 matches to create 2 squares.