Most breakfast cereals are fortified with vitamins and minerals including the ever-popular iron. However, the "reduced iron" they add is in the form of IRON FILINGS! Sorta hard to digest a real HUNK of iron, now isn't it!
Take a bowl of cereal that contains "reduced iron" or states on the box "Fortified with iron", I found that Total works wonderfully. Now, smash a handfull or two on your hands. (Where else would you smash a 'handful'?) and place in bowl. Now, splash on some milk like you are going to actually eat it. (Water is clearer to see through, but not as authentic-looking.) Stir this goop up vigorously till it gets to be like a broth. Let it sit for a minute or two to get all soggy and gross. Now, swish around a strong magnet like you are stirring it up. A cow magnet works good for this, but a Neodymium is great. Take magnet out and look shocked as you notice the amount of the iron filings. You will actually have a magnet coated with visible iron filings!
Can it be that we can digest actual pieces of iron? Certainly! In your stomach, the iron, Fe, reacts with your gastric juices, hydrochloric acid or HCl, to form FeCl, a compound easily absorbed thru the intestines.
Another cute this you can do with this? Place the smashed stirred flake goop made with water, NOT MILK, in a good ZipLock bag. Now, run a strong magnet along the OUTSIDE of the bag. You will quickly see iron collecting at the contact point INSIDE the bag like a simple etch-asketch. Cool effect.
Expanded LAB? Have the kids collect exactly one RDA of iron. That's Recommended Daily Allowance. You will need a good mg, MILLI-gram, mass scale for this. If you don't happen to have one sitting around, borrow one from your local college! Safety Note: I am a trained professional! (Trained in what, I don't know...) DO NOT lick the iron filings off the magnet! They are for show & tell ONLY! (It's amazing what you have to tell people NOT to do, ain't it?