Area of Parallelograms and Triangles - Lesson Plan [Show Teaching Plan Only]

Objectives

Teaching Plan

This eModule is split into five sections and a quiz, each with multiple activities.

Area of Parallelograms and Triangles (50 minutes)

Area of Parallelograms

The objectives of this lesson is for students to construct the formula for the area of a paralellogram.

1. (1 activity) Students create parallelograms by distorting a rectangle.

Students explain the relationship between the area of parallelograms and rectangles.

2. (1 activity) Students are presented the definition of base and height of parallelograms.

They are then guided through the process of comparing height and base with length and width.


3. (1 activity) Students are presented with an animation of the geometric relationship of paralellograms and rectangles.

Students then predict the formula for area of a paralellogram based on the formula for area of rectangles.


4. (1 activity) Students are presented with examples to calculate of area.

Area of Triangles

The objectives of this lesson is for students to construct the formula for the area of a paralellogram.

1. (1 activity) Students create triangles by cutting a rectangle and distorting the resulting right triangle.

Students explain the relationship between the area of triangles with the same base and height.

2. (1 activity) Students are presented the definition of base and height of triangles.

They are then guided through the process of comparing height and base with length and width.


3. (1 activity) Students are presented with an animation of the geometric relationship of triangles and rectangles.

Students then predict the formula for area of a triangle based on the formula for area of rectangles.


4. (1 activity) Students are presented with examples to find area of triangles.


Measuring Area: Addition Method

The objective of the second lesson is to teach students the addition method for finding the area of shapes with diagonals and to give them practice with the method.

1. (2 activities) Students find areas of figures by comparing them to triangles and rectangles.

2. (1 activity) Students explain how to find the area of a shape that has diagonal edges

Students find the area of the shape.


3. (1 activity) Students are presented with the algorithm for splitting a shape into rectangles and triangles and then adding the areas of all the pieces together.

4. (7 activities, 2 online) Students practice finding the area of shapes using the addition method.

5. (1 activity) Students are asked to describe how they would find the area of a shape containing an obtuse triangle.

Measuring the Area of Shapes with Diagonals: Subtraction Method

The objective of the second lesson is to teach students the addition method of finding the area of shapes with diagonals and give them practice with the method.

1. (1 activity) Students are presented with the algorithm for splitting a figure into rectangles and triangles and subtracting away the areas not included in the figure.

2. (4 activities) Students practice finding the area of shapes using the subtraction method.

3. (1 activity) Students are asked to describe how they would find the area of a more complicated irregular figure.

Creating Shapes of a Given Area

The objective of the third lesson is to have students create shapes of a given area.

1. (5 activities) Students create shapes with diagonals of a given perimeter.

2. (2 activities) Students create a figure with a given area and number of sides.

Students explain the process they used


Quiz

1. As the need arises, review concepts and processes with the class before having students complete the quiz.

2. (7 activities, 5 online) Students find areas of shapes and construct figures of a given area.


Assessment

Each section has its own online assessment.

Credits

Lesson Design Jim Dorward, Joel Duffin, Jennifer Jorgensen, Leo Edwards
Web Development Joel Duffin, Jennifer Jorgensen, Liz Hart
Mathlets NLVM

Correlation to Standards

Correlation to Utah Standards

Correlation to Maine Standards

Correlation to North Carolina Standards

Correlation to Massachussetts Standards

Correlation to Arizona Standards