Science tricks with eight-year olds?
November 24, 2010 3:19 PM   Subscribe

Science tricks to do at an eighth birthday party? Ones we did last year: candle doesn't pop water-filled balloon; small square of celluloid holds water in overturned glass; water and oil trade places in conjoined drinking glasses; corn-starch liquid/solid; paperclip floats on water. What are other easy-but-cool favourites?

(Interesting links appreciated too.)
posted by progosk to Sports, Hobbies, & Recreation (35 answers total) 88 users marked this as a favorite
Could you do stuff like making compasses by magnetizing needles stuck into corks so they float? I thought that was awesome when I was that age.
posted by naturalog at 3:31 PM on November 24, 2010

Best answer: Steve Spangler does a lot of cool science demos. My favorite is dry ice bubbles.
posted by griphus at 3:32 PM on November 24, 2010 [4 favorites]

If you have access to an outdoor area, the Mentos/Diet Coke thing seems to be popular.

The instructor for my science instruction methods class mentioned this book as being a good one for finding experiments for school age kids.
posted by lemonwheel at 3:35 PM on November 24, 2010 [1 favorite]

posted by griphus at 3:38 PM on November 24, 2010 [3 favorites]

Best answer: suck an egg into a bottle!
posted by nadawi at 3:42 PM on November 24, 2010 [1 favorite]

Best answer: Teach them about distribution of pressure and show them how difficult it is to squash an egg if you squeeze it lengthwise.
posted by holterbarbour at 3:55 PM on November 24, 2010

Carbonated fruit. Make some ahead of time, so you can show the process (and drop some dry ice into water and watch it bubble), and then have some already created, ready to eat.
posted by Cool Papa Bell at 4:00 PM on November 24, 2010 [1 favorite]

Response by poster: suck an egg into a bottle!

Ah, forgot to mention we did that one - good stuff!

My favorite is dry ice bubbles

Very cool. Looks a little complicated to set up though...


I wonder... would a kazoo, or some other instrument, be able to make that kind of effect? (So I can avoid the temptation to disembowel my speakers...)

Thanks - this is just the sort of stuff I'd hoped you all had up your sleeves!
posted by progosk at 4:00 PM on November 24, 2010

A bit like the water balloon, but the opposite: boil water in a paper cup.

Way more complicated, but "gold" plated pennies.

Bed of nails.
posted by mikesch at 4:12 PM on November 24, 2010

Best answer: Supercooled water.
posted by mikesch at 4:15 PM on November 24, 2010 [4 favorites]

Response by poster: Excellent stuff via Spangler, thanks griphus: easy stuff like skewering balloons looks perfect...
posted by progosk at 4:20 PM on November 24, 2010

(1) Add a few mLs of how water inside an empty coke can.
(2) Submerge can in a basin of cold water.

posted by onegoodthing at 4:28 PM on November 24, 2010

Best answer: Carrying on the soda can thread: You can fill a glass part way with regular 7up/sprite/some clear soda, then carefully pour diet coke on top and it will stay in 2 layers (dark on top/clear on bottom)

You can switch the sodas and show them the opposite - Regular coke on the bottom, diet clear on top.
posted by azlondon at 4:32 PM on November 24, 2010 [1 favorite]

Best answer: The question - how do you transfer water from a saucer to a glass using a slice of cucumber and three wooden matches?

(The water starts on the saucer). Put the cucumber on the saucer (should be thicker than the water is deep), put two matches in the cucumber, standing up. Light them with the third and flip the glass upside down over the matches and the water will be sucked into the glass. Kids love it.

I also know a great trick for balancing a pair of intertwined forks on the tip of a toothpick but I can't really explain it. I found this youtube video, but I don't know if it's really clear.
posted by scrute at 4:36 PM on November 24, 2010

Best answer: Static electricity and a stream of water. When I was a kid we did it with a plastic rod rubbed with rabbit fur and a stream of water from the tap.
posted by bonobothegreat at 4:45 PM on November 24, 2010

Best answer: A much easier dry ice experiment I did. Drag a wet soapy cloth across a bowl or mug with dry ice in it.

Touch a fork to dry ice and hear it squeal.
posted by just.good.enough at 4:59 PM on November 24, 2010

Best answer: I asked this question in February and got a lot of chemical responses, but this was my favorite household-items response from CathyG:
"Put a glass of Sprite on a tray.
Sprinkle black pepper to cover the entire surface.
Once that is fairly sturdy, pour salt into the center of the surface. When enough salt accumulates to be heavy enough to break the surface, it plunges into the Sprite and the whole thing fizzes over onto the tray."

We ended up doing a burning money demonstration, where you soak a dollar bill in an alcohol/water solution, hold it using tongs, and light it on fire. It was great- we had kids begging us not to light the money on fire, and they were amazed when it did. Beware, you may have to mess around with the water mixture proportions, we completely obliterated 2 bills before we figured out the proportions and did it in class.
posted by kro at 5:00 PM on November 24, 2010

Dang it kro, I came in here to recommend that again. Cafeteria fun!
posted by CathyG at 5:24 PM on November 24, 2010

extract DNA from a banana
posted by SueDenim at 5:29 PM on November 24, 2010 [1 favorite]

I entertained some kids (8-10 years old) for an entire day having them make rockets out of film canisters, water, and alka seltzer tablets. The link goes to Steve Spangler video. The kids got really into it - we had competitions about first one to launch, who could get it go the highest, and who could attach the most weight to it and still get it to a certain height. Wonderful way to emphasize independent and dependent variables and pretty easy clean up if outside or in garage. Have them change how much water they put in, whether the tablet is ground up. The key is not to use the black and grey film canisters.. use these. Go to Walmart or a film store and ask them if you could go through their giant bags of film canisters and take a dozen or so - I've never had folks tell me no.

Spangler also has this nifty density experiment but a simpler one is having kids float water on water. Get some cold (like ice cold) fresh water, cold salt water, and warmish (the warmer the better but you don't want to scald kids.. I hope...) fresh water and salt water. Color each sample differently and have them see how you can put the water in small glasses so that there are distinct layers of water. Make sure you have eye droppers (you can also float a small bit of craft foam between the layers so that the drops of water don't cause the water to mix. I do this with sophomores to seniors in HS when covering the Dead Zone in the Gulf of Mexico - I only give them the materials and tell them they have the next 40 minutes to model what happens when the Mississippi River meets the Gulf of Mexico... most get numerous combinations but realize that when rivers meet the ocean, there is warmer freshwater floating over cold salt water.
posted by adorap0621 at 6:02 PM on November 24, 2010

Sigh.. just remembered a few other simple things. Can you tell I'm a science teacher?

Have the kids make jello w/ pineapple - half with canned pineapple and half with fresh pineapple. The fresh jello won't set because of an enzymes that breaks down gelatin. For this age group, it just emphasizes that there is stuff in living things that do work and we can ruin that stuff (denature it) by things like heat and pH.

Get some balloons, water bottles, yeast, and a variety of sugars and see which sugar gets the yeast to produce the most CO2.

Cougar Hunt is more of a game that demonstrates carrying capacity and energy in a food web.

SueDenim's idea is great.. here's another set of instructions that gets rid of the heating portion.
posted by adorap0621 at 6:15 PM on November 24, 2010

If you feel like going big, make a cornstarch pool. Something kiddie pool-sized would work just as well and still be cool.
posted by missix at 6:43 PM on November 24, 2010

In elementary school I participated in Science Olympiad, and my favorite event was the egg drop. Each team or kid has to build a container for their egg out of readily available materials (newspaper, tape, cardboard, string, etc). You then drop the egg contraptions from increasing heights, until one contraption/egg survives.

You might need an old sheet to easily clean this up, and can do it at a park. Good use of random materials that usually lay around, and eggs are cheap.

Some egg drop ideas.
posted by shinyshiny at 6:48 PM on November 24, 2010

This might be tough with kids that young--I've tried it with middle schoolers and it was a big hit--but you can decide.
You need a bunch of empty plastic soda bottles, clean and dry, with caps. Ideally, one bottle per kid. The best size is 1-liter or smaller. It's very important that the bottles are dry inside.

1. Wet the top of the cap with a little water.
2. Flip the cap upside down on top of the open bottle. The water on the cap should make a little bit of a seal on the top of the bottle.
3. Place your hands on both sides of the bottle. Close your hands over the bottle, but don't squeeze. (It works best if your hands are dry.)
4. After a minute or two, the cap will start to "hop" on top of the bottle. (It does take a couple of minutes so it's good if you can be talking during this time to keep the kids from getting antsy--but don't tell them what's about to happen.) This happens because the warmth from your hands heats the air inside the bottle, causing it to expand. As pressure builds inside the bottle, it pushes air out the top of the bottle.
5. After the cap has been hopping for a few minutes, you can take your hands off, wait a minute, then turn the bottle upside down. The cap will magically stay on, even upside down. Once the air in the bottle cools to room temperature, the pressure inside the bottle decreases, so the higher air pressure in the room outside the bottle holds the cap on the bottle.
posted by pompelmo at 6:55 PM on November 24, 2010

why not light the candles on the cake with the sun and a magnifying glass?

2 round cake layers + creative cutting and frosting= paramecium cake
posted by sexyrobot at 6:59 PM on November 24, 2010

Kids are often a fan of Wint-O-Green Certs/Lifesavers sparking blue when bitten in the dark to demonstrate triboluminescence.
posted by ktrey at 7:57 PM on November 24, 2010

ending sexyrobot's lighting idea, with turning off the candles by adding baking soda to a small amount of vinegar in a glass bottle and then pouring the "air" (actually the generated CO2) over the candles, thereby extinguishing them with "nothing". OOhhh!!

(I read adorap0621's idea "Cougar Hunt" and thought "that's not quite age appropriate.." and then I read the rest of the description... I need more coffee...)
posted by alchemist at 1:54 AM on November 25, 2010

Make a pickle glow.
posted by knile at 2:13 AM on November 25, 2010

A little basic, but stick a soapy finger into a plate of water sprinkled with pepper and watch it scatter!
posted by alygator at 8:33 AM on November 25, 2010

Straight pin put into the crook of your arm, hold down the pin with one finger and then close down your arm, it won't stick you; I don't have kids and haven't been around near enough of them but that does seem liked, and probably it's not science but it is fun...
posted by dancestoblue at 8:59 AM on November 25, 2010

Make a homopolar motor.
posted by Akeem at 12:51 PM on November 25, 2010

Best answer: Milk, food coloring, and dish soap.
posted by mikesch at 1:44 PM on November 25, 2010 [2 favorites]

Response by poster: Just as a post-birthday summing up:

- I found Coke Light on Sprite to be surprising, and had planned to do a chapter on layering liquids (starting with oil and water, then coloured salt- and sweet water, and finishing off with the soda), but when I couldn't get the second one to work in my practice run, and also couldn't manage a three-layer soda, I decided to skip the layering stuff altogether for the more spectacular tricks I'd lined up.

- First up were balloons: the screaming one (with a ridged-edge coin whizzing around inside), and then the (un-screaming) skewered ones; it was actually pretty difficult to find the right size and quality of skewers for the size of balloons available. Cool to have them pop some, trying first, and then to surprise them with the pretty easy solution. (Last year I'd tricked them with pinpricking a balloon where I'd previously stuck a piece of scotchtape...)

- The fire chapter included (in a variation to the waterballoon that doesn't pop when held over a candle which had wowed them last year) bringing water to a boil in a paper muffin-cup over a tea-light (I could have gone for doing the egg, which I'd tried and managed with plain paper - rather than newsprint so as not to eat the ink&chemicals - over the gas rings, but I decided that water was surprising enough and also quicker to happen with just a candle to heat it); a failed attempt at a simple trick I remembered from when I was small: lighting amaretti wrappers to watch them float up to the ceiling; not sure what went wrong, maybe the room was too warm, but the wrappers just turned into very fine ash in the saucer; plus a simplified version of burning money, with the bill dropped into plain ethyl alcohol (the pink stuff) and then held up and flamb├ęd - for added effect, turn the lights low; big success, that one.

- I couldn't resist a brief non-Newtonian interlude - always fascinating.

- The final chapter was dry ice. (If you buy it in advance, find out about the forseeable loss by sublimation.) Main tricks were: just dropping it into (warmish) water and watching the reaction below the surface; pouring the foggy gas into their cups for them to "drink"; then the soapy cloth dragged across the opening of a jar with the bubbling water inside so as to grow a huge gas-filled mono-bubble; then adding soap into the water to get a suds-spewing volcano. Then, as a simplified version of Spangler's boo-bubbles set-up, I'd stuck a short piece of garden hose onto the nozzle of a sports-drink bottle, and made those individual cloud-bubbles they could all hold (easiest way was to have them pull their sweater sleeves over their hands) and pop. (We also used the contraption to inflate gas-filled, slightly "heavy" balloons.) One of the nice things about dropping dry ice into water is that after a bit you can pour the kids some chilled, carbonated water to drink. (It was interesting to discover that after a while the dry ice reaction slows down in any given volume of water that you've dropped a piece into, to the point that you can have pitchers of water with pieces of dry ice floating inertly in them; I was briefly mystified, until I realized that the water had probably become saturated in CO2, thus inhibiting further sublimation.) In my hunt for other, different tricks with dry ice I'd found two more that went down very well: to have a piece of ice "screaming" on a hard metal surface (in our case, the edge of a metal baking tray ), and finally the freezing pool of gas, with regular soapbubbles blown onto it that float, suspended, and actually freeze.

Other good tricks suggested here that I had lined up, but skipped for lack of time: psychedelic milk, liquid ice, and fire calling water. Other ones I'd done in the past and can recommend: bottled and crush-proof egg, and also bending water. One that didn't work for me was Sprite&salt (probably the wrong quality of pepper and salt, but it just sort of fizzled...).

Thanks for all the suggestions; the kids had a really memorable afternoon!
posted by progosk at 1:32 PM on November 28, 2010

Ferrofluid can be purchased online and, so long as you have a good container (I use accidentally non-sterile these), you can entertain kids for a good half hour with it. You can also make it yourself, though I wouldn't recommend trying it in a kitchen as the processes to make the nanoparticles are either extremely messy or pretty dangerous without a hood.

I made my own with some old chemicals but I had access to an O Chem lab with hoods, balances, and glassware.
posted by Blasdelb at 5:26 PM on December 1, 2010

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