What Is the Area of Your Classroom?
Students will be able to calculate the area of real-life rectangles, such as the area of the classroom.
- Ask students to look around their classroom and estimate how big it is. Listen to student responses. Probe how they would find out exactly how big the room is.
- Tell students that when they are adults, they will look for an apartment or house to live in and that usually people like to find out the square footage of the place, or how big the space is.
- Explain to students that today they will practice how to find the area of a rectangular room and emphasize that the area is the entire space inside the rectangle.
Explicit Instruction/Teacher modeling(10 minutes)
- Tell students that to calculate the area of a rectangle we must multiply the length by the width. Write A = L x W on the board and leave the equation visible for the remainder of the lesson.
- Ask students to consider a room that has the length of 10 feet and a width of 3 feet. Draw a model rectangle and demonstrate how to find the area (A = 10 x 3 = 30 square feet). Emphasize the importance of writing the unit correctly (i.e., square feet).
- Display the Kitchen Renovation: Calculating Area worksheet on the document camera and read the directions aloud. Model to students how to calculate the area for the whole kitchen and subtract the area of the kitchen counters, sink, and oven. Remind them of the equation for area each time you find the area of a rectangle.
- Give students time to ask questions or clarify any doubts they have as you model how to solve for area on the worksheet. If time permits, complete the challenge at the bottom of the worksheet.
Guided Practice(10 minutes)
- Distribute the Practice Finding Area #5: Pick the House worksheet to students and display a copy on the document camera.
- Read the directions aloud and model how to solve for the area of the first house.
- Instruct students to work in small groups to find the area of the rest of the houses on the worksheet.
- Circulate and offer support to groups that need help.
Independent working time(15 minutes)
- Pass out a piece of scratch paper to each student.
- Tell them that they will find the area of the classroom by sketching a rectangle on their scratch paper. (Note: if time and space allows, assign each group a different room in the school such as the library or the cafeteria.)
- Model how to use the measuring tape or yardstick to determine the length and width of a room, and encourage students to work together with each person completing their own sketch and calculations.
- For students who need more support, have them use graph paper, with one square unit representing one square foot.
- Group students in heterogenous groups so that they can learn various strategies from each other.
- Instruct students to find the area of their whole house.
- Pass out a sticky note to each student to use as an exit ticket.
- Draw a rectangle on the board (18 feet by 12 feet) and tell students to calculate the area of this rectangle.
- Use this exit ticket to determine whether students have met the objective.
Review and closing(5 minutes)
- Restate the equation to find the area of a rectangle (A = L x W).
- Discuss with students the following question: In what situations is it helpful to know how to find the area?