Lesson objective: Fluently extend understanding of opposites as points reflect across the x or y axis.

This lesson helps to build fluency with recognizing coordinate pairs that are reflections across the x or y axis and with naming a reflection of a point across a given axis. The coordinate plane is used here because it allows students to physically see given points reflected across the x or y axes. This work develops students' understanding that points (a, b) and (-a,b) are reflections about the y-axis and (a,b) and (a,-b) are reflections about the x-axis.

Students engage in Mathematical Practice 7 (look for and make use of structure) as they apply their knowledge of the coordinate plane, coordinate pairs and opposites to reflect points across the x and y axes.

**Key vocabulary:**

**Special materials needed:**

- scrap blank coordinate planes