5th Grade Lesson Plan on Adding and Subtracting Fractions

The Number Line

• Draw a number line on the blackboard or on the worksheet, and use it for all of the problems. The number line is a horizontal line with zero marked in the middle. To the right of the zero, the positive numbers appear in increasing order. To the left of the zero, the negative numbers appear in decreasing sequence,

Adding and Subtracting Positive Numbers

• To add a positive number to anything, point to the number with which you are starting and count to the right the value of the positive number. For example, to add five to two, point to the two and count five numbers to the right: seven. To add 5 to negative two, point to negative two and count five numbers to the right: three. To subtract a positive number, do the same thing but count to the left. The teacher should do several examples, and then end with the student feedback activity described earlier.

Adding and Subtracting Negative Numbers

• Show the students how the directions change when adding and subtracting negative numbers, Start the same way by pointing to the first number, count to the left for adding negative numbers and count to the right for subtracting negative numbers. The teacher should do several examples and end with student feedback.

Common Denominators

• Demonstrate how to find common denominators. Use a simple method, instead of finding the lowest common denominator -- this can wait until later. Show the kids how to locate fractions on the number line by dividing up the distances on the line by the denominator of the fraction. The teacher should do several examples and end with student feedback.

Adding and Subtracting Positive Fractions

• Provide a few examples of how adding and subtracting fractions is similar to adding and subtracting whole numbers, except that you only count up the numerators and you are counting subdivisions of the number line –- the divisions based on the common denominators. The teacher should do several examples and end with student feedback.

Adding and Subtracting Negative Fractions

• Adding and subtracting negative fractions is similar to adding and subtracting whole numbers, except that you only count up the numerators and you are counting subdivisions of the number line. The teacher should do several examples and end with student feedback.