At the request of some young friends I am having a day of cool science this Friday.
So far I have organised an experiment with diet cola + mentos.
Non Newtonian fluid with cornflour and water
Separating colours using a black marker and a coffee filter + water.
Making silly putty or slime or bouncy balls using borax and PVA glue: at the moment I have quite a number of different “recipes” for these three and if any fols out there have a no fail one they would like to share with me I would be greatful.
I would also like suggestions of other cool things I could do with the coffee filters.
Any other suggestions for cool (easy to do at home) sciencey stuff would be apreciated. I would prefer actual desciptions and techniques rather than links please (besides just when I needed them kitchensinkscience.com is offline)
What age group are we talking about here? Stuff that’s “cool” for seven year olds won’t make teenagers even blink.
Younger kids can be impressed by simple air pressure experiments. One I recall involved a candle, a pan of water, and a jar. Fill a cake pan with an inch or so of water, put a candle (tall enough that the water won’t snuff it) in the middle of the pan and light it. Invert the jar and place it over the candle, down in the pan. In just a few seconds, the candle flame will slowly die as it runs out of oxygen. As it does, the water inside the jar will slowly rise as a result of the drop in pressure due to the oxygen in the jar being combusted. Simple, but neat to a kid.
For older kids, a somewhat more dangerous one, with a simple lesson: stuff that doesn’t traditionally burn will burn if it’s broken up into smaller pieces. Burning steel wool works, but my chem teacher once did something along the following lines: large metal coffee can, with a hose attached to one side. He then (and I’m going from memory, so I probably left out some steps) placed the can over a lit candle and a small plate of flour. The plate was positioned near the hole where the hose entered the can. Stepping back to a safe distance, he blew mightily into the hose, causing the flour to disperse into a cloud within the can. Shortly thereafter, the flour burned/exploded with a mighty WHUMP, tossing the coffee can quite high into the air. Really brings home the point of why silo fires are so dangerous.
Have a metal container of at least 1 gallon, and with a screw-on lid. Place small amount (1 or 2 cups) of water inside and heat to boiling. Screw on the lid tight and dunk it immediately into a larger container of ice-water. It will crunch down to a fraction of its original volume and make a very satisfying “CRUNCH”.
It demonstrates the vapor-to-liquid volume transition due to temperature changes.
I just did this last weekend. A couple of suggestions:
1.) Paper towels are WAY faster than coffee filters. If your kids get bored easily, paper towels are the way to go.
2.) Instead of black magic markers, use a collection of colored felt-tips. And be sure to use WASHABLE ink, which separates and flows easily. You’ll find that a lot of markers don’t well at all.
Other things I’ve done:
1.) Make paper cup telephones or, better yet, tin can telephones. After the kids have made a pair and used them ((you have to pull tight on the string, unlike what’s shown in cartoons, or it won’t work), ask them if you can add a third cup and have a three-way telephone. Try it. Try adding more phones to your network. Is there a limit to how many you can add? What’s the best way to add them?
2.) Build a spectroscope using a CD or DVD and a cardboard tube. Look at different light sources, or look at a white light source through different filters.
3.) Besides Coke + Mentos, you can try other experiments in which you fill a ballon with gas from a reaction. If you put one component in the bottle and the other in the balloon, then attach the ballon to the mouth of the bottle first, then you can dump the balloon contents into the soda bottle and watch the reaction. This is a lot better than trying to slip the balloon on against a raging reaction. You can try
Vinegar and Baking Soda
Water and Pop Rocks
Water and crumbled Alka-Seltzer tablets
4.) Another person at the same event had the kids male small Cartesian Divers. You’ll have to do some prep work for that.
There are others, but I wouldn’t recommend them with small kids.
Get a bottle, some vinegar, baking soda, and a balloon. With a funnel, put a couple of teaspoons or so of b. soda in the balloon (stretch it out pretty good first). Put some vinegar in the bottle. Put the mouth of the balloon around the mouth of the bottle, and then hold the balloon so the soda falls in. After the furor dies down, you will have a balloon full of CO2, which is heavier than air. Play with the balloon–it goes thunk!
Now light some candles in votive holders and try making CO2 in an open measuring cup with a spout–I had most luck with a good tall one. Hold your hand over the top to prevent the CO2 spilling out–it’s heavy so it ought to stay, but it’s good to be careful. Pour the CO2 over the lighted candles and they will go out. (Tea candles work well and they must be in votives or it will just go everywhere and not last long enough.)
If you have an older crowd, you can make hydrogen in a balloon (outside) by mixing Liquid Plumr and aluminum foil in a bottle with a balloon on top. Tie the balloon to a stick and a match to another stick, and explode the H. Boom!
Get some sulfur in a lump, crush it into bits, and try burning it. Do this outside. You can get sulfur at a rock shop or maybe a gardening place–people use it on their gardens.
Another fire one–you can relight a candle after blowing it out without touching the wick. Have a burning candle, set a match on fire. Blow out the candle and hold the burning match in the smoke, close to the wick. The wick will relight. You can do this about 4 times before your match burns down.
Take a heavy button. Put a loop of thread through 2 holes in the center. Put a pencil through each end of the loop. Hold the pencils and swing the button around to twist up the thread. Now pull the pencils apart to get the button spinning. When the thread is almost unwound relax your grip on the pencils and let the momentum rewind the thread. Then pull the pencils apart again. By repeating this process you can keep the button spinning back and forth. This is a demonstration of momentum and transfer of energy. The best part is that it is a toy the kids can make by themselves.
Wasn’t that sold commercially many years ago? Or maybe it came as a prize in a cereal box? I distinctly remember playing with something like that. I even remember how it felt. But I have no idea where it came from.
Take a piece of Bristol board (like the cardboard that shirt collars are packed with), and cut a little boat out of it - maybe an inch long. Just make it vaguely triangular. Cut a small notch in the “stern” of the boat (the base of the triangle). Shave some soap to make flakes. Take a flake of soap, and wedge it in the notch you cut, so it hangs down like a rudder. Carefully set the boat in a sink full of still water. The boat will start to zip around the water - as the surface tension of the water is reduced at the rear of the boat. The bigger the surface of the water, the longer the boat will move.
The kids involved are girls - 11, 13 and 14. They had originally requested explosions so i may tray the flour fire one. I will have to be very careful though as Friday is looking like a total fire ban day.
I am also thing of making some “hot ice” sodium acetate from vinegar and bicarb: Anyone here tried this?
For the biology minded, you can isolate DNA from wheat germ.
Place about a tablespoon of raw, not toasted wheat germ in a small bottle or jar with a lid. Add enough water to cover and add a good shake of meat tenderizer and a squirt of liquid soap. Put on the lid and shake for about a minute. Let the wheat germ settle to the bottom, then pour the liquid into a clean, clear glass. Try not to carry over any wheat germ. Slowly layer on a roughly equal amount of isopropyl alcohol. In a minute or two, you should start to see white strings forming at the interface. That’s the DNA precipitating out of the solution. The kids can wind the DNA like a thread onto toothpicks. You can also do the precipitation in a capped bottle and invert it after adding the alcohol. This results in a big knot of DNA, but it is a bit quicker and more active.
You can do the same experiment with other strongly-coloured foods - blackberries and blueberries work well, as does beetroot, even turmeric, apparently.
I love this idea. And, for the record, I disagree with Frannyy’s criticism that you are too vague. For kids, that’s about as much explanation as they can handle. In a college level chemistry or botany course, I would go for her explanation.
This can be done on a smaller (and cheaper) scale with an aluminum soda can. Take an empty soda can and put a couple of tablespoons of water in it. Heat it until the water is boiling. Have a small pan nearby with some ice water in it. Using tongs, quickly move the soda can from the heat source and immediately invert it (open end down) into the ice water. It will be instantly crushed. It happens so fast the kids’ll probably want to see it more than once, so have a few cans handy.
A VERY easy Cartesian diver: Fill a 2 liter plastic soda bottle with water. Take one unopened packet of Arby’s Sauce and put it in the bottle. Screw the cap on the bottle. The Arby’s Sauce packet should be slightly bouyant, and will be floating at or just under the water’s surface. Squeeze the sides of the bottle and the packet inside should dive toward the bottom. I haven’t tried any other type of condiment packets, but I know that Arby’s Sauce usually works. A ketchup packet might work well, too.
Another simple and cool thing to do is make matchstick rockets. All that’s needed is some paper matches, aluminum foil, a needle, and a paper clip. They’ll fly several feet, and often leave a little smoke trail. They will be very hot after firing, though, so make sure and launch them outside–perhaps on pavement.
A non-exploding demonstration on a quieter day might be to place cut celery stalks into colored water to demonstrate capillary action.
Fire-related: Also, show them how a nine-volt transistor radio battery can turn steel wool into a handy-dandy ignitor, in case they ever need to start a campfire and they happen to have transistor radio batteries and steel wool, but no matches.
Oooh! or a white carnation in a small vase of blue food dye. Snip a little bit off the bottom end of the stalk before putting it in there - after a while, veins of blue will start to appear in the petals.