Education Technology

# Fractions / Adding Fractions with Unlike Denominators

Activity 7 of 15
This lesson uses unit squares to help students investigate addition and subtraction of fractions with unlike denominators.

## Planning and Resources

Objectives
Students should understand that when adding fractions, the fractions are marked off end to end on a number line. If the denominators are different, the fractions can be added by creating equivalent fractions that have the same denominator, then use the process for adding fractions with like denominators.

Vocabulary
congruent
common factor

Standard:

## Lesson Snapshot

#### Understanding

As students explore the concept of adding fractions, they should begin to see that a common denominator will always be the product of the two denominators.

### What to look for

If the denominators do not have a common factor, the rectangles in both unit squares are congruent. If the denominators have a common factor, however, the rectangles are not necessarily congruent, as displayed in the file.

### Sample Assessment

If one part of a recipe calls for  (2/3) cup of milk and another part of the same recipe calls for (3/4) cup of milk, how much milk do you need all together for the recipe?