Tensile Strength
Tensile Strength is how much pulling force a material can handle before it breaks apart.
Think of it this way
A strip of plastic wrap is stretched flat between two blocks on a counter. Small weights hang from a tray at the center of the strip. A thin strip tears under less weight, while a thick strip holds more. The weight that finally rips the strip is its breaking limit.
Explaining tensile strength by grade level
Pick up a strand of hair and pull both ends gently. It stretches a little before it snaps. Some hairs break faster than others. That tells you how strong each strand is when you pull on it.