My 5-year-old loves doing “science experiments” at home with me and her older siblings, but it seems that the online lists of experiments we’re choosing from are truncated to leave off all but the least dangerous activities. This makes sense for a lot of low-parental-involvement contexts, but I’m going to be directing and deeply involved in these experiments. And I want fire. Smoke. Sparks. I want to make these experiments feel adventurous so the kids get really excited about whatever we’re learning. Baking soda and vinegar volcanoes and elephant toothpaste just don’t cut it.

What experiments can you recommend using only relatively common household materials? Chemicals, candles, electricity, a stovetop, etc. (Assume that the experimenters will all be taking standard precautions, wearing PPE, and generally using the experiments as both an opportunity to learn about science and about the safety measures that go with science experimentation.)

Or if you know of any websites listing these more spectacular home science experiments, please share those as well.

Bonus if the experiments involve multiple possible outcomes that the kid can use pen and paper and elementary math to predict in advance.

I am looking for practical ways to prove the Earth is round using materials accessible to the average person. I have zero interest in disproving Flat Earth folks.

I am inspired by Dan Olson's (Folding Ideas) excellent video where he is able to do this measuring the curvature of a lake near his home that has a very specific geography that lends itself to this sort of experiment. I've seen all sorts of ways to prove this measuring shadows and poles, using gyroscopes, etc. and wanted to know if there are any practical guides for proving once and for all that the Earth is round for yourself relying on nothing more than experimentation.

What I'm not looking for:

• Math relying on flight times/charts
• Video/picture evidence
• Deductive proofs built on agreed upon premises
• Expensive tests
• Extremely time consuming projects
• Underwhelming results (relying on a probabilistic argument for a round Earth from the evidence.)

What I am looking for:

• Practical experiments
• Things I could potentially do without spending much money
• Tests that aren't largely comprised of accepting someone else's research
• Potentially math-heavy evidence
• Results that are strong and conclusive

I've thought of finding some easy to test version of Eratosthenes' proof using two poles. I've also thought about using a balloon and sending something to space like what is done in this Tom Scott video. Nothing seems well documented in such a way as for me to be able to follow it at home.

TL;DR: I think it would be a meaningful experience to have the power to prove the Earth is round by myself, for myself. I can only compare this desire to the desire a child with a telescope has when wishing to observe Saturn or Mars themselves for the first time. It's not to prove anything or to settle doubts, but for the personal value of independently observing this astronomical fact oneself.