Here is a simple device that can be implemented by a manually challenged person, which illustrates the concept of chaos - i.e. very small changes producing disproportionally large effects. This is concept is a centerpiece of the argument abou the climate/environmental change - small (human inflicted) changes can gave disproportionally large effects.
Ingredients: a clear plastic tube, diameter 2-3 inches, and length about 4-5 feet; a small bouncing ball (it has to be bouncing!) that fits inside the tube, and empty aspirin or similar plastic bottle that fits inside the clear plastic tube, a particle or plywoood board (a thick, rigid cardboard will do) about 1ft x 1ft, a rectangular piece of plywood, thick plastic or rigid cardboard approximately 2 x 6 inches, a round piece of wood about 3 inches long and diameter that snugly fits inside the clear plastic tube, Elmers glue, automotive or similar goop.
Step one - glue the round piece of wood to the center of the particle or plywood board Step two - cut two narrow slots on each side (but the same end!) of the clear plastic tube- as wide as the thickness of the rectangual board; proceed as follows: start on the end of the tubing and go up about 6 inches (the total length of the cut should equal the length of of the round piece used in step 1 plus the length of the shorter end of the rectangualr piece used in step 3; make an identical cut on the other side. Step three - cut the rectanhular piece of wood or cardboars diagonally - the end result will be two right triangles Step four - cut off the neck of the plastic aspirin bottle, take the bottom part and make two slots on the end - similar to those you did in the clear plastic tube, but much shorter, perhaps 1/2 in long Step five - take one of the right triangles created in step 3, and attach the plastic bottle from step 4 (using sluts) to the MIDDLE of its _longer_ side in such a way that the hypotenuse is facing down and the bottom of the bottle is facing up, use goop to fasten the bottle to the triangular piece Step six - insert the piece created in step 5 to the slot of the clear plastic tube, the attached bottle going in first; insert the second triangle created in step 3 so the hypotenuse of this piece fits against the hypotenuse of the first piece (with the bottle attached) Step 7 - put the whole assembly on the round wooden piece from step 1 (pretty much like a condom) in such a way that the plastic bottle inside faces up; use small nails to attach clear plastic tube to the round piece of wood
At this point, pulling the lower triangle back and and forth will move the plastic bottle inside the tube up and down, like a piston.
To demonstrate the random effect, do as follows:
Drop the bouncing ball inside the tube - it will start bouncing up and down until it comes to a rest - please note that the hight that the the ball reaches in the "up" cycle of the bouncing can be easily predicted.
Then repeat the procedure, but this time start moving the lower triangle back and forth to slightly raise and lower the "piston" inside the tube (you may need to do it quite fast) - at this time the ball will bounce quite irrgularly and the hight of the bounce will be unpredictable; in other word, the small changes in the position of the piston (off whichthe ball bounces) will cause the boll to bounce either much higher or much lower than the original change.
PS. A vistit to a local science museum (a nerdy thing, I agree) can give you some ideas as well.
Wojtek