Find Area

Introduce Square Centimeter Halves and Fourths. Display and direct students' attention to the Square Centimeter Halves and Fourths section of the Shapes on Grids pages in the Student Activity Book. Tell them that sometimes a shape includes both whole and partial square centimeters. This page asks students to identify 1 square centimeter, a rectangular one-half square centimeter, a triangular one-half square centimeter, and a square one-fourth square centimeter. Ask students to work with a partner and see if they can find the area of each shaded shape in Questions 1–4. They can record the areas with the words "one-half" and "one-fourth." Remind them to include the unit, square centimeters.

Upon completion, discuss Questions 1–4. Question 4 is likely to require the most discussion. Divide the whole square centimeter in the question into four equal parts on the display.

For Question 5, ask students to draw simple shapes on the grid with an area of 2 and one-half square centimeters. See Figure 9. Encourage students to create as many different shapes as they can by using whole, half, and fourth square centimeters.

Instruct students to exchange papers and have a partner verify the areas of their shapes.

Find Area of Shapes on Grids. Assign the remaining problems, Questions 6–14, on the Shapes on Grids pages. Students find the area of shapes including shapes with half and fourth square centimeters. Remind students that they can write numbers on the shapes to help them keep track as they find the area. Circulate as students work, noting different solution strategies for Questions 11–13. Ask these students to be ready to present their solution strategies to the class.