The next unit we cover is on circles and area. Here is a copy of our unit objective page for the unit. It will cover the following topics:

• Calculations with the area of parallelograms

• Calculations with the area of triangles

• Working with pi, radius, diameter and circumference of circles

• Calculating the area of circles

• Interpreting circle graphs

• Creating circle graphs

We started with a review of some skills taught in 6th grade, including calculating area and perimeter of rectangles.
Here is a quick video that shows how to calculate the area and perimeter of rectangles
This second video is longer, but nicely demonstrates the difference between area and perimeter (and important concept to understand!)
Here is some practice for calculating the area and perimeter of rectangles

1. Parallelograms 

The next shape we explore is the Parallelogram. These are shapes that have 4 sides, and have opposite sides that are parallel and congruent. Other examples: rectangles, and squares! 

To find the area of a parallelogram you must use the formula: Area = base * height, or better known as A = bh 

Here is a video to help explain the concept.

Here is some practice (all include answer keys):

• Worksheet 1 - Find the area

• Worksheet 2 - Find the area

• Worksheet 3 - Find the missing height or base.

2. Triangles 

Next, we focus on working with the formula for the area of a triangle. 

• Here is a video to help with understanding the formula for area of a triangle

• Here is a video showing a few different calculations

• Here is some standard practice & some more

• Here is some practice finding height or base when given area & a video explaining how to do so

3. Circles
Circumference of circles (including diameter, radius and pi)

The next topic covered is circumference (perimeter) of circles. First, students learn the definition of diameter and radius. Next, we learn about the circumference of circles, while exploring the relationship between diameter and circumference, which leads us to learning about pi.

Here is a video introducing and explaining radius, diameter, circumference and pi (explaining how they are related and showing some calculations)

Here is a video showing how to convert from radius to diameter

Here is a video just showing how to use the circumference formula if given diameter

Here is some practice calculating circumference when given diameter or radius

Here is a video showing how to find diameter or radius when given circumference

Here is some practice finding radius and diameter when given the circumference

Here is some practice with circumference word problems

Area of circles

Next, we covered calculating the area of circles.

Here is a video explaining calculating area of circles (note that students HAVE to use the radius. If given a diameter, they must divide by 2 to get the radius)

Here is some practice (with answers)

Here is some word problem area and circumference practice & answers 

Here is a video on finding radius from the area

Here is a set of worksheets (with answers) that practices this concept