What are the supertitious beliefs in science?

Spinning an egg to see if it is boiled or uncooked- if it is wobbly, it is uncooked. otherwise, it is not.

Immersing an egg in cold water to see if it is fresh or old- if it floats it is old, if it sinks it is fresh.

Adding yeast to bread dough and covering the dough with cloth and leaving it alone for a few hours before baking- the cloth keeps insects from contaminating the dough and the yeast creates small holes in the dough filled with carbon dioxide making the bread rise.