No, I don’t want anyone here to do my kid’s homework for her, but I would like some suggestions as to what an appropriate science fair topic would be. She’s supposed to come up with a question to explore by next week, and I honestly can’t think of anything to suggest. Does anyone here have any suggestions for a fun, educational, and/or interesting subject?
Thanks in advance from Harborkid.
What kind of things are they already studying in class? (It’s been a few years and I don’t recall the exact 3rd grade Science syllabus.) 
They’re studying the solar system. I’m stumped.
I think I built a model of the solar system.
I also did a test of cleaning products on different stains on different surfaces. Got lots of free samples from the local hardware/home store, got three or four different cleaning products, set up an experiment and went to town.
Elementary school science specialist checking in here. I probably won’t be any help, but I must chime in regardless.
I think science fairs are a waste of time.
Especially for elementary school kids.
Particularly if participation is required.
And most definately if the projects are judged and prizes awarded. I think they may be responsible for turning more kids off of science than having to memorize the periodic table.
Why? Because they are based on a false premise. The premise is that children will conduct long-term, novel research and design their own experiments as they investigate. Bull. Two days before it’s due, they recycle the same tired topics and canned experiments to produce mind-numbingly dull models, charts and graphs. Or, and this is worse, their parents “help” them produce a staggeringly sophisticated project worthy of NSF funding. The goal is worthy, I suppose. But science fairs have morped into the antithesis of science. There is no fun, no curiosity, no risk, no QUESTION!
For instance, how on earth is an 8 year old supposed to conduct research or perform experiments concerning the solar system? I’m not saying it can’t be done. But do you think a 3rd grade will be able to come up with a question—on her own—and research it—on her own—and design experiments to test a hypothesis—on her own? Nope.
Anyway, this is of no help to you whatsoever. So, here are a couple of questions that might spark your child’s interest and maybe get him/her started. I think I may have read some of them on the Dope.
Animals fly, crawl, creep, walk, run, swim…why don’t any roll? How come animals haven’t developed with wheels for appendages? (He/she could experiment with wheels and see why tissues would be unsuitable for rotation)
Why aren’t there any really big insects? VW sized bugs for instance? (He/she could look at exoskeletons and how heavy an exoskeleton might be on a large insect)
Why don’t underwater plants produce flowers? (He/she might put different flowers under water, shake them, twist them, observe them…what happens?)
I agree with a lot of what you said, and I agreed with it when I was a kid doing science fair projects several years ago. Unfortunately, the elementary school doesn’t care if I think that the science fair is a waste of time, shouldn’t be required, and will never spark a lifelong love of science. She still has to participate with an experiment, data, results, and a big, giant display of her “research.”
Thank you for your suggestions. I think they’re great. I’ll run them by the kid and see if any interest her.
Howzabout static electricity? She’s certainly familiar with the rubbing a balloon on your hair to stick to the wall type, as well as the walk across the carpet in socks and get zapped on the metal doorknob, surely. Learning about which everyday items will hold a negative or positive charge might be interesting. She already understands like charges repel and unlike attract from playing with magnets, positive and negative charges shouldn’t be a difficult next step.
A fairly simple project could be suspending a hard rubber rod and a glass rod of similar size across one of those tri-fold display board things, and keep two more rods as hand pieces. Rub the hanging ones with a piece of wool to induce a charge, rub the hand ones and use the invisible charge to force the hanging one to move. Have two or three different rubbing materials, like wool, silk and nylon fabrics maybe, and chart which ones cause a positive/negative charge.
Yeah, as a parent I like it because it’s simple, non-explosive and cheap, but I gotta admit it’s pretty likely to bore a kid, sorry.
Mom of little(ish) kids who like the science fair checking in…
Our most popular project was the home-made barometer. They each followed it for about three weeks. That was plenty of time to learn about air pressure, watch the weather man (boy, were they happy when he made incorrect predictions!), track the results, etc. Our best project was germ growing.
Consumer surveys are popular at school (best valued for your money, taste tests, best product for the job) as are experimets with plants. These are popular because they are short and easy. We don’t find those so interesting, ourselves.
Anyway, the best way to pick a project is to start in the area where your kid is most interested. My kids like space themes. Any project is a boring chore if the kids don’t like the topic.
Chocolate chip cookies for science!
Start with the recipe on the toll-house morsels. Now, how can she make thinner cookies? Softer cookies? Crisper cookies? She’ll learn to change only one variable at a time (temperature, cooking time, ingredient), and record her observations carefully if she wants to get meaningful results.
I was always a fan of the product testing portion of science fairs. I won an award at State for testing the relative absorbancy of various brands and styles of diapers. Which paper towel really is strongest when wet? What type of battery lasts the longest? What style of hair stretchy is the stretchiest?
Here’s a simple one: Vaccuums and air pressure.
Get a Snapple bottle, or any bottle with a wider mouth, and hard boil an egg. Light a match and toss it into the bottle, and then put the egg over the mouth of the bottle. The egg will be slowly sucked into the bottle by the vaccuum.
Of course, check to make sure lighting a match would be permitted by the school. Some won’t allow a fire.
Nitrogen triiodide 
Or you could be like me and build a crappy radio that doesn’t work. But I think exploring precipitate colours might be kind of cool, if you have access to lab reagents. Or get a pH meter and test the pH of various solutions you find around the house.
Of course, to be good science, the project should note that nothing gets sucked by vacuum* and that the egg is actually pushed by the higher air pressure outside once the air inside has reduced in density as it cools.
Hey, figuring out why it happens is HER job! 
How about something with the weather? Weather fascinated me as a child.
Something like, “Why doesn’t it snow in July?”
Build a potato powered clock and then compare it to clocks powered by other vegetables, such as beets, turnips, kohlrabi, brussel sprouts, carrots, and corn. Explain which veggie is best and why. After the science fair, slice up and eat the project.
I just got a request from a neighbor kid to have my reflexes tested by playing “connect the dots”. Each person would be timed and the times charted vs, their age. Not sure it’s good for you, as you have to located a fair number of people to get a sample. But it’s easy enough.
She could do the “5 second test”. She could take food, maybe a cookie, drop it on the floor, and test it for bacterial contamination at differing time periods. All she’d need are RODAC plates, food, and a floor.
RODACS are about $60.00 for twenty, and if you talk to your local hospital lab, or food lab, and they’d probably give them to you at discount, or free.
These were really popular when I was in Jr High. Pick an activity, like connecting dots, doing a maze, solving a puzzle, etc. Make people do it right hand only, left hand only or while listening to different kinds of music or while standing versus sitting, etc. Guess who will be better and why (ie, kids will be faster at connect the dots because they do connect the dots in school, men will be faster than women 'cause girls are dumb, etc.) and then see if your are right. A couple books about the brain, and a nice big poster board and you have a science fair project with a real hypothesis.
How about mixing science and animals?
Static electricity and Cats.
Rub the cat’s back on your leg and see if the animal sticks to the ceiling.
My now 15-year-old daughter won the third grade science fair with an interactive experiment. She brought in a scale and asked people to weigh themselves and she showed how the differing forces of gravity on each planet would change their earth weight. It was very simple. She also won in 2nd grade by building a constellation box and writing the history and mythology of each of the constellations she had available to view in the box. In both cases, I think the judges could tell she did the work herself (her project board was hand-written and I did not correct her spelling errors) and thus she won over some of the more complicated, but obviously parent-assisted, projects.