This lesson was used with a tier 3 fourth grade intervention math group to help students understand inverse relationships with addition and subtraction. I found this activity on Illustrative Math and I modified it to meet the students' needs. I modified the lesson by using just page four of the Triangle Worksheet attached resource from the Fact Families Illustrative Math lesson. I used only this page because I wanted students to understand the 8 related equations of fact families, rather than just the 4 equations.