When you were little, you probably read the Dr. Seuss book Green Eggs & Ham. Here's a little pH trick to make some green eggs just like in the book.
Red cabbage contains pigments called anthocyanins, which change colors when they come in contact with acids (low pH) or bases (high pH), making them a natural pH indicator. When the cabbage juice comes in contact with an acid (like vinegar) it will turn red, but when it is mixed with a base it will turn bluish-green. What does this project tell us about egg whites, then? Egg whites are basic (also called alkaline) and so they turn the red cabbage juice green.
Make a regular egg float in a 250 ml beaker! Use a funnel to pour a layer of salt water underneath a layer of water. Do this by placing place the tip of the funnel at the base of the baker filled halfway with fresh water. Make sure its pointy side is up against the side of the beaker. Carefully add an egg and watch it float. Raw eggs float in salt water, but sink in fresh water.