Lesson 04 – Strength and Stability

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Read About Strength and Stability


Read the vocabulary terms to understand the reading better.

Balance is the ability to stay in a controlled position and not fall over.

A load is the mass or weight supported by something.

To jiggle is to move in quick little jerks up and down or side to side.

Stability is when an object can keep its balance and stay in place.

A structure is something that is made from different parts and joined together in a certain way to support a load.

To sway is to slowly swing back and forth or from side to side.


A structure has to be strong enough to hold its load. A chair is a structure. The person who sits on the chair is the load. If the chair is not strong enough, the chair will break when someone sits on it.

A paper cup does not have to be nearly as strong as a building. The liquid in a paper cup does not weigh very much.


We say that a structure is stable when the structure can keep its balance and stay in place.

It is easy to keep your balance when you stand on two feet. Standing on two feet keeps you stable. Keeping your balance when you stand on one foot is harder. When you stand on one foot, you are not as stable.
You might sway back and forth, so your body does not stay in place.

Have you ever tried to create a very tall stack of nickels? When the stack is short (less than 25 nickels), it is stable. The stack does not sway or jiggle much when you add nickels. Once the stack has about 40 nickels, it jiggles and sways much more. A short stack of nickels is more stable than a tall stack of nickels.

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