A good book about Chemistry for the middle school and high school: “A Demo a Day, A Year of Chemical Demonstrations”, by Gross, Bilash and Koob. It has “Separating Metallic Iron from Cereal”, the simplest form of which is to put iron-fortified cereal in a plastic bag with a magnet and shake. “Many cereal companies add fine powdered iron to their cereals as the U.S.RDA for iron. Most people assume that cereals are fortified with a soluble ionic form of iron and not iron in its elemental form. Once ingested, the iron will react with the acid in one’s digestive tract to form iron ions which in turn may be absorbed into the body.”
“Potato Candle” describes how to make a candle using a cylinder of potato as the candle wax and a Brazil nut for the wick. It is designed to show the importance of observation, while grabbing the students’ attention. The teacher who wrote this demo was big on showmanship; after simply telling the students that they are observing a candle, he turns out the lights and asks them to write their observations. He blows out the candle before it burns out and asks them to read their work aloud. “Someone will see the wax melting, the braided wick, the carbon dioxide and water vapor coming off. Remind them about observation and interpretation and how they might have to change their conclusions on the basis of new evidence.”
“If you have timed this correctly, there will only be about one minute left in the period. Now eat the candle and walk out of the room – never tell them what it was!!! This will convince your classes that you are an eccentric. There is a lot to be said for this.”
There’s good variety in this book, so you might like to look at it.
I notice that there are similar books of demonstrations for the physical sciences, biological sciences, etc. But they appear to be out of print! If anyone knows a good source for these, please post it! Flinn Scientific appears to carry it (and here’s the Physical Science book).