Lesson objective: Apply the skill of counting whole and half square units to estimate the area of curved figures using partial square units.

This lesson provides an opportunity for students to apply their knowledge and understanding of counting square units to determine the area of a plane figure to a real-life situation. Students are asked to estimate the area of three curved flowerbeds in order to find out how many bags of fertilizer will be needed to cover them.

Key Concept students will use:

- 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 square units

Skills students will use:

- use graph paper to count square units inside a plane figure
- combine partial square units to form additional whole square units
- add two digit numbers (Grade 2, Unit 1)

Students engage in Mathematical Practice 2 (reason abstractly and quantitatively) as they count whole and partial square units to estimate the area of the three curved figures.

**Key vocabulary: **

- area
- estimate
- partial square unit
- square foot
- square unit
- tally
- whole

**Special materials needed:**

- colored pencils, crayons, or markers
- flower bed blackline master (in Additional Materials)