**Cheez-It Math**

Full lesson as word document: Cheezit Math

Area and Perimeter

**Objectives**:

- Students will understand the meaning of area and perimeter and have experience using manipulatives to visualize the concepts.
- Students will explore relationships between area and perimeter and recognize that shapes with the same area can have different perimeters, and vice versa.
- Students will hear and use mathematical language in context including: area, perimeter, prime, square, factor.

**Supplies**:

- Cheez-Its (2 boxes is good enough for a class of 30)
- Worksheets (included in word document linked at beginning)

**Lesson**

- Give each student (or pair of students) 16 Cheez-Its. Have each student assemble a Cheez-It rectangle.
- Find the area and perimeter of that rectangle in “Cheez-it” units (which are about 1 x 1 inch; ‘generic’ brand tend to be smaller). For area, count the squares (“area, square-y-a”); for perimeter, trace the
**lines**on the edges (“perimeter – the line around the edges”) - Display different rectangles with 24 Cheez-its. Review the concept that area means the space taken up in two dimensions or two directions, while perimeter is one dimension, like a straight line.
- Draw rectangles of those sizes on the grid paper; look for patterns (e.g., the more like a square the rectangle is, the smaller the perimeter will be). Note that the scale is smaller – the rectangles on the paper will have perimeters in centimeters and area in cm
^{2}. - Be sure to include 1 x 16.
- Note that the lengths of the sides are “factors” of the area number.
- Encourage students who are counting from one to practice working with larger numbers in their thinking (so if the area was 8 x 2, to trace the line for the perimeter but know that it is going to be 8 w/0 counting each line again).

** **

** EAT 2** **CHEEZ ITS – or set them aside if you’re disinclined to do so. **

** **Repeat the pattern above with 14 Cheez-Its. Note that you can make fewer rectangles with 14 Cheez-its. (Don’t draw all the rectangles… we’ll pick our favorites at the end. )

** **

**EAT 2** **CHEEZ ITS **

** Repeat the pattern above with 12 Cheez-Its. **Note that you can make lots of different rectangles…

**Eat 1 CHEEZIT: **

** **Repeat the pattern – note that you can only make a 1 x 11 rectangle… this is what makes 11 a “prime” number.

**Eat 2 CheezIts: **

Repeat the pattern – note that you can only make the looong rectangle and… the nice square.

** **

** Eat 5 Cheez-Its… **

Repeat the pattern – note that you can only make the looong rectangle and… the nice square.

** ARE YOU SICK OF CHEEZITS YET???? **

** **

**EAT 3 CHEEZ ITS**

Repeat the process with 1 Cheez-It. (Note: A perimeter of 4 sometimes confuses them. Make sure they count the edges.

When the process is done, discuss data in groups. Draw conclusions. What patterns do they see? Have students record conclusions on back of Record Sheet.

Pick your four favorite rectangles and draw them on the grid paper, and note their areas and perimeters.

**Possible Discussion Points**

- Discuss what would happen if you compared rectangles with the same perimeter. (The more the shape looks like a square, the larger the area will be. The more the shape looks like a line, the smaller the area.
- What would happen to the area if you doubled the side of a given square? For example, instead of a 2×2 square, you would have a 4×4 square. (The area actually quadruples when the side is doubled.)

**NOTE**

Adapt! Do fewer or more “repeat the procedure” as befits the situation.

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Posted on May 23, 20160