Adding and subtracting fractions is a concept first taught in fourth grade. In previous grades, students have been taught about ordering, comparing, and equivalent fractions. Now they are ready to take what they have learned and apply it to addition and subtraction.
One way to teach this concept is through number lines and picture models. You can draw a pizza on the board (divided into eighths) and write down as many addition equations as possible to show how to add up to 8/8 or 1 whole pizza. You can act this out with your students. This introduction allows you to explain how you only add the numerators.
Once you have done this activity, you can represent it on a number line. Have your students draw a number line to show eighths, and then have them represent their addition equation on the number line.
After you have taught addition this way, you can do the same thing, just reversed, for subtraction.
