Before starting this activity, revisit what “numerator” and “denominator” mean, stressing that the denominator gives the name to the fraction. When adding fractions, you are adding parts; as long as you are adding the same kind of parts (common denominator), you only need to worry about how many parts in all. In this activity, students will add or subtract two fractions using visuals to help explain the process.
Give students examples of when you might add parts together, but be careful of how you word your questions!
“Dennis ate 2 pieces of pizza and Larry ate 2 pieces of pizza. How much pizza did they eat?”
Is the answer four pieces? Four-eighths? All of the pizza?
Be explicit in the question or example. Identify how many pieces make up the whole. Use precise language when asking the question, such as “what fraction” or “how many pieces”, so students know what they are looking for.
By rewording the story, you can use the same example for subtraction. You can change the question to “what fraction of the pizza is left” or “how many pieces are left?”
Just as in subtraction with whole numbers, be sure students are writing the numbers in the correct order. Typically, students have not yet encountered improper fractions, and certainly not negative numbers. The larger fraction goes first in the number sentence: 3/4 - 1/4 = 2/4.
(These instructions are completely customizable. After clicking "Copy Activity", update the instructions on the Edit Tab of the assignment.)
Student Instructions
Practice adding and subtracting fractions with common denominators based on the question in the first cell.
Engage students with a fun, interactive game that helps them practice adding and subtracting fractions using common denominators. Games increase motivation and build confidence by making learning collaborative and enjoyable.
Use tangible materials like fraction tiles, strips, or homemade cards to give students a concrete way to visualize and combine fractions. Having hands-on tools supports all learners and makes abstract concepts easier to grasp.
Promote teamwork by having students work together to solve fraction problems. Collaboration encourages discussion, peer teaching, and boosts engagement.
Provide practice problems that use the same denominator, such as 2/8 + 3/8 or 5/6 - 1/6. Scaffold the difficulty to ensure all students succeed and understand the process.
Encourage students to physically combine or remove pieces to model the equation. This hands-on approach makes the math visible and helps students explain their thinking.
Facilitate a class conversation about the strategies used, common mistakes, and what helped them understand. Reflection deepens learning and connects practice to real-world math.
The easiest way to add fractions with the same denominator is to add the numerators together and keep the denominator the same. For example, 2/8 + 3/8 = 5/8.
To subtract fractions with a common denominator, subtract the numerators and keep the denominator unchanged. For example, 5/6 - 2/6 = 3/6. Use visuals to help students see the parts being taken away.
Visual models help students understand how fractions represent parts of a whole, making it easier to see how the pieces combine or are removed. This builds a strong conceptual foundation before moving to abstract calculations.
Common mistakes include adding both numerators and denominators, or not clearly identifying the whole. Emphasize that only the numerators are added or subtracted, and the denominator stays the same.
Teachers can explain that the numerator shows how many parts are being counted, while the denominator tells how many equal parts make up the whole. Using real-life examples, like slices of pizza, reinforces this concept.