Classic jigsaw puzzles are good fun for people of all ages.
When two pieces fit perfectly you are quite certain this is correct. and you can continue with the remaining pieces.
In fact the puzzle gets more simple after each placed piece. Normally there exists only one solution.

Links to classic jigsaw puzzles:

Mathematic jigsaw puzzles are the opposit.
You often find pieces that fit perfectly, but you have no clue that this is correct.
You often aren't much closer to any solution until the last piece fits! There often exist more than one solution, sometimes milions !
But if they are simple ... I'll leave it up to you.

Puzzles with squares

Puzzles with only square pieces may seem very simple, but size does matter!
Polyominos are a large collection of puzzles. All pieces are built of number of triangles, squares or hexagons. Ever played Tetris? You're in advance!
Tenyo's 'Beat The Computer' puzzles

Tenyo's 'Beat the Computer Series' are a set of varied mathematic jigsaw puzzles, They could easily keep you busy for some weeks.

Links to classic jigsaw puzzles: