Pass out the link cubes to the students. Be sure they have two sets in two different colors. These will represent fractions, which are equal parts of a whole number.
Break off five math link cubes. Four should be in one color and one should be another color. Explain to the students that all five cubes represent a whole number and the denominator. The four link cubes that are the same color represent the part of the whole number, or the numerator.
Write on a chalkboard the first fraction made with the cubes, or 4/5. The denominator is on the bottom, while the numerator is on the top of the fraction. There are four parts of the whole number 5.
Point to the single cube that is another color. This cube would represent 1/4; write it on the chalkboard next to the first fraction, 4/5.
Ask the students to add the two fractions together, 4/5 plus 1/5. Ask students what the result would be. Link the different colored cube with the others. Ask students what the answer would be. It would equal 5/5, which is a whole number.