Beacon Lesson Plan Library
DescriptionEntice students to investigate perimeter with one of their favorite foods. Students use a variety of methods to measure the perimeter of a piece of cheese, infer the change in perimeter before slicing it and recalculate the perimeter.
ObjectivesThe student uses a wide variety of concrete objects to investigate measurement of length, weight, capacity, area, perimeter, and volume (for example, cubes, grid paper, string, squares).
Materials-Individually wrapped American cheese squares
-Tangram puzzle pieces
-Centimeter grid paper(include this if extension activity will be used with lesson)
-Copies of Cheesy Math Log
-Copies of Cheesy Math Checklist
-Overhead transparencies of Cheesy Math Log worksheet with marker
-Overhead transparency of centimeter ruler
-Overhead transparency of centimeter grid paper
Preparations1. Make copies of Cheesy Math Log for each student.
2. Make copies of the Cheesy Math Checklist for each student.
3. Gather individually wrapped American cheese slices, plastic knives, centimeter rulers, centimeter cubes, 12” X 12” waxed paper squares, tan gram puzzles for each student.
4. Make transparency of Cheesy Math Log work record, and centimeter ruler.
Procedures1. Ask "Have you ever eaten a sandwich with American cheese on it?" Hold up a piece of cheese and ask what shape is it?
2. Say a square is a polygon and all polygons have a perimeter. Can you tell me what a perimeter is?
3. Encourage students to define perimeter as the distance around something. Point out that the word [perimeter] has the word [rim] in it. A perimeter is the rim around the shape.
4. Ask how could I measure the perimeter of this piece of cheese?
5. Invoke responses such as [use a ruler, centimeter cubes, paper clips].
6. Distribute Cheesy Math Log, Checklist, tangram pieces, and centimeter cubes to each student.
7. Assign peer partners (“elbow partners”) for explaining procedures for measuring perimeter.
8. Demonstrate on overhead, using centimeter cubes around the outside of different tangram pieces, to find the perimeter. Count cubes aloud with the students to reinforce.
9. Have students use centimeter cubes to investigate the perimeter of three different tangram pieces and record their measurements on the Cheesy Math Log.
10. Ask students to explain correctly to their peer partner, “elbow partner”, their procedures and perimeter measurements. Circulate about the classroom to formatively assess student responses.
11. Distribute centimeter rulers, waxed paper squares, and squares of American cheese to each student.
12. Demonstrate on the overhead measuring perimeter of piece of cheese using a transparent centimeter ruler.
13. Have students place cheese on the waxed paper, measure the perimeter of the cheese using a centimeter ruler, and record their results in the Cheesy Math Log.
14. Ask students to report their results to their “elbow partner”. Circulate around classroom checking for accuracy.
15. Demonstrate on the overhead cutting a rectangular chunk out of one side the cheese using a plastic knife, trace around the cheese using overhead pen, and ask students to predict the perimeter of the cheese now.
16. Measure the cheese on the overhead to find the perimeter. Discuss the results of cutting. Is the new perimeter larger or smaller than the original perimeter?
17. Ask students to make inferences about why the perimeter increased or decreased.
18. Distribute plastic knives to each student and instruct students to make similar cuts in their piece of cheese, trace around the cheese on the back of the Cheesy Math Log sheet, measure the perimeters after each cut, and record the perimeters.
19. Repeat step 17 two more times. Circulate the classroom checking student’s procedures for accuracy.
20. Encourage students to infer how cutting chunks out of the cheese changes the perimeter.
21. Ask students to write a conclusion about perimeter based on their discoveries in the Cheesy Math Log.
AssessmentsThis lesson assesses measuring perimeter to the nearest centimeter only.
Evidence: Circulate around the room, to formatively assess students engaging in measuring procedures. Provide corrective feedback as needed. Teacher uses completed Cheesy Math Measurement Log (refer to associated files) to formatively assess the student’s ability to use real-world objects to investigate perimeter and solve problems in measurement.
Criteria for Cheesy Math Log:
• Accurately measure the perimeter of three tangram pieces using centimeter cubes.
• Accurately measure the perimeter of a square of American cheese using centimeter ruler.
• Accurately measure the perimeter of a square of American cheese after cutting out pieces and tracing it in Cheesy Math Log; repeating the process three different times using a centimeter ruler.
• Correctly explain the procedure for measuring perimeter to the teacher.
• Correctly explain, in the Cheesy Math Log, how cutting out pieces of the cheese affected the perimeter.
Assessment tool: A checklist formatively assesses student Cheesy Math Measurement log (refer to associated files). Each student receives the checklist (refer to associated files) with the Cheesy Math Log.
ExtensionsStudents use centimeter graph paper to create as many rectangular arrays possible with 24 square centimeters, and record the perimeter of each rectangle.
Students use tangram puzzle pieces combined to make irregular polygons, trace around the created shapes, use a centimeter ruler to find the perimeter of the shapes, and record the perimeters.
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