Make sure that they enter the numbers for the fractions correctly. Explain to students how the denominator in the answer is the common denominator for each of the two fractions being subtracted. Be sure to emphasize that students are working with fractions with unlike denominators. Step 4 Complete the fraction problem by finding the fractions equal to 1 Ask the students what they multiply 4 by to get 12. Then stress the notion of equivalence.
Fractions have to be equivalent.
So, the fractions in the brackets must be equal to one. Then work through the answer. You can finish the exercise by comparing the answer with the visual representation that the students drew in Step 1. A template for these problems can be found in the file addsubfr.doc . You can change the problems simply by going through each step and changing the fractions and the signs.