Applying the Area Formulas for Regular Polygons

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SWBAT apply the area formulas for regular polygons.

Big Idea

Students find the area of polygons.

Do Now

10 minutes

In the previous lesson, Developing Area Formulas, students developed area formulas for regular polygons.  The Do Now focuses on the area of a rectangle, but students need to think logically about the problem.

Do Now

A rectangle measures 3 in by 4 in. If the lengths of each side double, what is the effect on the area?

Students may initially think that the area doubles because each side length doubles.  I will suggest to students that they actually calculate the area of both rectangles, to determine the affect on the area.  Once students have done this, they will realize that the area quadruples.

Independent Practice

15 minutes

For the Independent Practice students will use the area formulas to help them complete the Finding the Finding the Area of Regular Polygons Worksheet.  Although students should work independently, they may want to discuss or ask questions of their group.

Students will have 15 minutes to complete the worksheet.

Group Work

15 minutes

Students are heterogeneously grouped.  I will assign each group a problem from the Finding the Area of Regular Polygons Worksheet. Students should discuss their work and answers with their group.  When they are in agreement, I will give groups chart paper and colored pencils for them to show their work.  Students will have 10 minutes to complete their work.

After 10 minutes, the group work will be posted around the classroom for a roundtable activity.  For this activity, students should have the worksheet and their work with them.  Students will rotate to each group work.  At each problem, students will review the completed work and compare it to their work.  Post it notes will be available for students to write comments or ask questions.  After the groups have rotated to each problem, they should end back up at their chart paper.  I will give the groups time to reflect on any comments or questions they may have received.  If there is any confusion, we will discuss it at this time.

Exit Ticket

5 minutes

At the end of this lesson students will be given an area problem to solve.  The results of this exit ticket will be used for future grouping.

The challenge of this problem is that the area and base is given, but students have to work backwards to find the height.  Also, the base is given as a decimal, so students may have difficult finding 1/2 of 0.18.

Exit Ticket

Fran is surveying a plot of land in the shape of a right triangle. The area of the land is 45,000 sq meters. If the base of the triangular plot is 0.18 km long, what is the height, in meters, of the triangle?