Changing the Way We Teach Math

Egg Carton Fractions^{Footnote 2}: With empty egg cartons you can demonstrate equivalent fractions, proper and improper fractions, and addition, subtraction, multiplication and division of fractions using a whole dozen, half a dozen, thirds, fourths, sixths, and twelfths of a dozen. One advantage of egg carton fractions is that students can make them themselves and inaccuracies of cutting do not render them useless, since it is the number of cups that makes the fraction, not the precise size of the cut.

Further, it is clear that six egg cups is half a dozen, whether the six are in one long row, or two rows of three. Other advantages are their cheapness and their stackability!

To make a set of egg carton manipulatives, you will need six empty egg cartons. Start by taking the lids off them all. Then work on the bottoms. Leave the first carton whole (12 egg cups). Cut the next in half (6 cups in each half). Cut the next into fourths (3 egg cups in each quarter), the next into thirds (4 egg cups in each third), the next into sixths (2 egg cups in each sixth) and the final one into twelfths (1 egg cup in each twelfth). Students can stack various pieces inside each other to show that 6/12 equals 1/2, that 3/4 equals 9/12 and hence is larger than 2/3, which equals 8/12, and so on. You can ask students to do the fraction demonstrations starting on page 72, using these egg carton manipulatives, but they will be able to demonstrate only questions with denominators of 2, 3, 4, 6 and 12.