Rain gauges are easy to make.
You will need:
* an empty 2-liter plastic bottle
* scissors or exacto knife
* paper clips
* some clean pebbles, marbles or glass beads
* masking tape
* a ruler
* permanent marker
How to make it:
Carefully cut the bottle as straight as possible just below where it widens so that you have a consistent width all the way down. Fill the bottom of the bottle with enough pebbles or marbles to fill in the bottom and give it enough weight so that it doesn't blow over. Remove the cap and place the top upside-down inside the wide opening and fasten with paper clips or tape, lining up the two cut edges. The spout will now act as a funnel. Use the tape to make a straight long verticle strip down one side of the bottle. With your marker, make a line a little above the top of the pebbles. This will be the bottom of your gauge or the "0" mark. Now, with a ruler, carefully mark every quarter (or eighth) inch above that 0 mark on the tape. Set the bottle on a level surface and fill with water until it reaches your 0 mark. Now find the perfect spot to put your new rain guage. It needs to be a level spot that's not too windy where it won't get disturbed by animals or playing children. You will need to check it once in a while, especially if you think it will rain, to make sure the water hasn't evaporated. Check it after a rainfall to see how much rain actually fell. You can keep track in a notebook. Older kids can figure out average rainfall and so much more.
When I was a kid, I loved learning about clouds. There are so many different shapes and sizes. There are Cirrus, Stratus, Cumulus and combinations of each of those. Here is a great website that shows how to make your own barometer, how to make a cloud in a bottle, how to make fog and how to suck an egg into a bottle. You can also build a tornado machine out of just a few supplies.
You will need:
* 2 1-liter plastic bottles
* a metal washer that will fit flush over the bottle opening
* duct tape
* glitter or very small "debris" (optional)
How to make it:
Remove the caps off of the two bottles and fill one with water up to an inch from the top. Put whatever debris you'd like into the water. This is optional. Place the metal washer on top of the filled bottle. Place the second bottle upside-down on top and duct tape securely. To make your volcano, turn the bottles over and swirl the top water-filled one in one direction. The direction doesn't matter. Soon, a whirlpool will form, just like the whirlpool in a bathtub when it's draining. Try swirly slowly and quickly to see what difference it makes. Try flipping the bottles over without swirling. You can learn 10 fun facts about tornadoes at this National Geographic Kids website.
There are so many simple things to do at home. You can teach your children about evaporation and rain by putting boiling water into a mason jar and put the lid on tightly. Make sure they don't touch the hot bottle and burn themselves. As the hot water starts to cool, it will condense on the sides and top of the jar. The drops of water on the top will get heavy and "rain" into the jar. You can have rainbows in your home by hanging crystals in a sunny window or find them in glasses of water. As always, if your kids are interested, use your imaginations to find more things to do or look online. There are tons of great science sites out there. And, don't forget to have fun!