How many shapes do you know?
Use your fun time at the beach to educate your young ones and test your own memory with seeing how many shapes you can remember, the sand is a great canvas to draw and create just about anything.
Try all the different shapes you can think of, either draw them in the sand or make 3D versions.
While you're at it spell the words out, this helps with character recognition.
Heres a few to get you started:
Octagon, Circle, Decagon, Diamond, Heart, Heptagon, Hexagon, Nonagon, Oval, Pentagon, Rectangle, Square, Star, Trapezoid, Triangle