Circle graphs
Circle graphs (also called pie charts) display data as sectors of a circle, where each sector's size is proportional to its share of the total. In Grade 6 Saxon Math Course 1, students find each sector's fractional size by dividing the category count by the total, converting to a percent or decimal, and relating it to 360 degrees. A category representing 25% of the total occupies 25% of the circle (90°). Circle graphs make part-to-whole comparisons immediately visible.
Key Concepts
Property Circle graphs, which are sometimes called pie graphs or pie charts, display quantitative information in fractions of a circle.
Examples Total items: For a graph showing 10 cars, 5 trucks, and 5 bikes, the total is $10 + 5 + 5 = 20$ vehicles. Finding the fraction: If 5 out of 20 vehicles are trucks, the fraction is $\frac{5}{20}$, which simplifies to $\frac{1}{4}$. Finding the percent: Since $\frac{1}{4}$ of the vehicles are trucks, that portion of the graph represents $25\%$ of the total.
Explanation Imagine your data is a giant pizza! A circle graph, or pie chart, slices it up to show how much of the whole each part represents. Instead of just reading boring numbers, you can see at a glance which slice is the biggest. It's a super visual tool for comparing parts of a group to the entire thing.
Common Questions
What is a circle graph?
A circle graph (pie chart) shows quantitative data as fractions of a circle. Each slice's size is proportional to its share of the whole.
How do you find what fraction of the circle a category represents?
Divide the category's count by the total: Fraction = category ÷ total.
A survey of 40 students shows 10 prefer soccer. What fraction of the circle is that?
10/40 = 1/4. That slice occupies 1/4 of the circle, or 90°.
How many degrees correspond to 25% of a circle graph?
25% of 360° = 0.25 × 360 = 90°.
When is a circle graph more useful than a bar graph?
Circle graphs are better for showing part-to-whole relationships; bar graphs are better for comparing quantities across categories.