A bead is a small, pretty object with a hole through the middle so that many beads can be threaded together to make a chain.
Beads can be made of clay, glass, wood, shells, stone, nuts or in fact anything that looks good and might be nice strung together.
Beads are usually strung into necklaces or bracelets.
A cell is the building block of life. All living organisms are made up of cells. The simplest organisms, like bacteria only have one cell, while larger creatures like trees and animals are made up of millions of cells.
Different types of cell in your body do different things. For example, there are special cells that make your bones and your brain that aren't very much alike, but are both types of cells.
Cogs are the small "teeth" around the edges of gears. Cogs allow the gears to grip onto each other as they turn around.
