Lesson objective: Measure the area of plane figures by counting square units.

This lesson helps to build procedural skill with finding the area of plane figures. Square tiles and graph paper are used here because they support students' understanding that we count square units covering a figure to measure area. This work develops students' understanding that square units or unit squares (that cover a figure without gaps) can be used to measure the area of a figure, which is said to be *n *sqaure units.

Students engage in Mathematical Practice 2 (reason abstractly and quantitatively) as they count unit squares to determine the area of plane figures. They use square tiles and squares on graph paper to count the number of square units that cover a plane figure. They begin to understand that different shaped figures can have the same area.

**Key vocabulary:**

- area
- plane figure
- square unit
- tile
- unit square

**Special materials needed:**

- square inch tiles (if none are available, there is a printable set of square inch tiles under the Additional Materials tab)