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Math Lesson- Area of a Parallelogram
Objectives:
- Students will review the properties of parallelograms and develop and use a formula for the area of a parallelogram
Materials:
- 2 long straws, short straws per child
- 4 twist ties per child
- Example of parallelogram
- Rulers
- Math journals
- Math master p.122
- Scissors
- Tape
- Math link 2.6
- Transparencies
- Overhead projector
Set:
Math message- give students pre- made bags of 2 short straws and 2 long straws and 4 twist ties. Instruct them to construct
a parallelogram using the 4 straws and twist ties. Model this activity for them so the students understand what they need
to do.
Teaching:
1) Whole class activity: Using their constructions, have students tell you what they know about parallelograms, the properties
of a parallelogram.
- 4 sided polygon, called a quadrilateral- polygon with four sides
- opposite sides are parallel
- opposite sides are the same length
- rectangles and squares are special kinds of parallelograms
Have students make a rectangle using their straws, and then ask them to gently pull the opposite corners. Pose the question
of the parallelogram they just made: does the perimeter stay the same? YES. Does the area stay the same? YES.
2) Show the class the parallelogram that you have made ahead of time. Show them that one side is the base, or length or
the parallelogram. Show them that the shortest distance between the base and the side opposite the base is the height. Model
this on the parallelogram- draw a dashed line to show the height, include a right angle symbol.
3) Give students Math Master 122 and have them open to journal page 250. Have students cut out parallelogram A and cut
it into two pieces to form a rectangle, tape into journal. Discuss the relationship between the parallelogram and rectangle.
Model this for the students using the enlarged copies of the parallelograms. Measure the base and height of each rectangle,
multiply to find the area.
4) Have students repeat with parallelogram B, be sure to model it for them if they are having trouble. Then have them
complete C and D on their own, then go over as a class.
5) Bring students together and discuss the formula for the area of the parallelogram
Guided Practice:
-Journal page 252. Go over #6 as a class so students understand what they are to do. Have students complete the page in
partners, then go over as a class, discussing each problem.
Homework:
- Study Link 8.6- area of parallelogram. Go over the paper as a class and complete # 1 and #5
- Study Link 8.6- percents in my world
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