"The balance is essentially a lever of the first class, having equal arms. The beam carries a pan at each end, one for the weidhts used, the other for the article to be weighed." -Avery 1895

Balance

"The balance is essentially a lever of the first class, having equal arms. The beam carries a pan at…

Illustration showing optical illusions. It is not always possible to trust the eye to be sure if the lengths of lines a and b are the same. You would need to measure to be sure of your conclusion.

Optical Illusions

Illustration showing optical illusions. It is not always possible to trust the eye to be sure if the…

Illustration showing optical illusions. It is not always possible to trust the eye to be sure if the lengths of lines a and b are the same. You would need to measure to be sure of your conclusion.

Optical Illusions

Illustration showing optical illusions. It is not always possible to trust the eye to be sure if the…

Illustration showing optical illusions. It is not always possible to trust the eye to be sure if the lengths of lines a and b are the same. You would need to measure to be sure of your conclusion.

Optical Illusions

Illustration showing optical illusions. It is not always possible to trust the eye to be sure if the…

Illustration showing optical illusions. It is not always possible to trust the eye to be sure if the lengths of lines a and b are the same. You would need to measure to be sure of your conclusion.

Optical Illusions

Illustration showing optical illusions. It is not always possible to trust the eye to be sure if the…

Illustration showing optical illusions. It is not always possible to trust the eye to be sure if the lines are the same distance apart. You may need to measure to be sure of your conclusion.

Optical Illusions

Illustration showing optical illusions. It is not always possible to trust the eye to be sure if the…

Illustration showing optical illusions. It is not always possible to trust the eye to be sure if the lines are the same distance apart. You may need to measure to be sure of your conclusion.

Optical Illusions

Illustration showing optical illusions. It is not always possible to trust the eye to be sure if the…

Illustration showing optical illusions. It is not always possible to trust the eye to be sure if the lines are prolongations of the other lines. You may need to measure to be sure of your conclusion.

Optical Illusions

Illustration showing optical illusions. It is not always possible to trust the eye to be sure if the…

Illustration showing optical illusions. It is not always possible to trust the eye to be sure if the lines are prolongations of the other lines. You may need to measure to be sure of your conclusion.

Optical Illusions

Illustration showing optical illusions. It is not always possible to trust the eye to be sure if the…

An illustration of a rectangle with lengths a and b and area ab.

Rectangle with Lengths a and b with Area ab

An illustration of a rectangle with lengths a and b and area ab.

An illustration of composite rectangle with lengths a, b, and c with area ac + bc. This illustration represents the product of c(a+b).

Rectangle with Lengths a, b, and c with Areas ac and bc

An illustration of composite rectangle with lengths a, b, and c with area ac + bc. This illustration…

Sawhorse used to length of legs.

Sawhorse

Sawhorse used to length of legs.

An illustration of a hollow square (square within square) with outer square having a side of 2s+6 and inner square having a side of s-2. Illustration could be used for calculating area.

Hollow Square with Dimensions of 2s+6 and s-2

An illustration of a hollow square (square within square) with outer square having a side of 2s+6 and…