Course Guide - USAID Teacher Education Project

Denominator. We can also use this method to compare fractions, noting here that 3/4fills 9 of the cells whereas 2/3 only fills 8. Thus, 3/4 is greater than 2/3.)If we overlap the rectangles, the overlapping portion is 3/4 of the 2/3. Count theoverlapping squares. The overlapping portion is 6/12, or its equivalent, 1/2.8. How children think about these conceptsa. When working with fractions children commonly look at an addition or subtractionexample and simply add (or subtract) the numerators, then add (or subtract) thedenominators. Thus in the example above for 5/8 + 3/4 it would not be uncommon fora child to come up with a mistaken answer of 8/12. In subtraction, this same type ofthinking might result in 3/4 - 5/8 = 2/4 with the youngster reversing the minuend andthe subtrahend.b. As mentioned in the session on multiplication, because of whole number thinking,children often assume that multiplication always “makes things bigger” than its factors.c. When multiplying fractions (unlike when adding and subtracting them) you do operateacross the numerators and across the denominators, multiplying each.9. What is essential to know, or do in classa. Present the concept of the GCF and LCM, how to find them, and how they are usedwhen working with fractions.b. Address how operations with fractions are both similar to and different from operationswith whole numbers.c. Provide students with visual models and strategies to help them conceptualizeoperations with fractions.d. Relate each of the above to children’s thinking