Two thirds represents the largest part of the whole. The smaller the denominator the larger each unit is.

Fractions as Part-Whole concept is the most commonly used example to teach fractions to children. A fraction represents one or more parts of a geometrical figure which has been divided into some equally-sized pieces.

Probably the most commonly used fraction is 1/2, which is one-half. When you cut a cake into two pieces and take one for yourself, you get 1/2 of the cake.

We call the top number the **Numerator**, it is the number of parts we have. We call the bottom number the **Denominator**, it is the number of parts the whole is divided into (Numerator / Denominator).

You just have to remember those names! (If you forget just think "Down"-ominator).

Know more about the basics of fraction at Dummies.com and MathisFun.com.