I love simple toys. Your basic blocks. The ball. A good book. Add to that list the little ol' magnifying glass. It doesn't have to be a fancy one you get at science class -- a plastic toy one will do. Carrying around this amazing instrument can bring a new view on the world with each step...and tap into that everyone's inner Sherlock Holmes. Say it with me: Elementary, my dear Watson!
It's cool to see what your kids discover with a magnifying glass. Everything is up for grabs, of course, but outside, be sure they examine leaves, sticks and any creepy-crawly creatures they may find. Ask your kids to list what is different from each view of the objects, what they see now that they didn't before - from little hairs or streaks of color or tiny ridges. They can even start a little journal, drawing what it looked like without the tool and then up close.
Inside has just as many cool discoveries to make. Get a new perspective on food, like crackers or fruit. Look over artwork and photos. Another cool idea -- get a stamp pad, and have your kids make a fingerprint on a piece of paper. You do it too, and examine how every print is different (neat crafty byproduct: you can then turn those prints into cute little pictures by adding eyes, feet and what ever else you want).
Don't have a magnifying glass? Use water. Cover a page of book or magazine with saran wrap and add a drop of water to it and see if the letters under the droplet look different than the others.
Do your kids have a magnifying glass? What do they love to explore with it?