8th Grade Percent Increase and Decrease Quizzes

While introduced earlier, percent increase and decrease concepts are solidified and applied in more complex ways in 8th grade. Students use these skills as a foundation for understanding linear equations, functions, and scientific notation.

Move beyond basic calculations to problems that require algebraic thinking. For example, provide the final price after a discount and ask students to write and solve an equation to find the original price. You can also connect percent change to linear functions, exploring how a constant percent increase (like simple interest) creates a linear pattern of growth over time.

Focus on problems that require setting up and solving equations. Examples include: 'A shirt is on sale for $28 after a 20% discount. What was the original price?' Also, introduce problems with repeated percent changes and comparisons, such as determining whether a 20% increase followed by a 20% decrease results in the original value.

A key misconception is believing that a percent increase and a subsequent percent decrease of the same value will cancel each other out. For example, students may incorrectly assume that a 10% increase followed by a 10% decrease returns the value to the original amount. Working through this specific scenario helps correct this error.

This quiz is available as a printable PDF for hands-on practice and as a digital quiz on the Wayground platform. For students needing extra help, you can use the 'Read Aloud' feature in the digital version. For all students, the included answer key provides immediate feedback for both independent and guided practice.

In the Common Core progression, 8th grade is a bridge between proportional reasoning and linear functions. Understanding percent change helps students analyze linear relationships, particularly in the context of simple interest (y = P(1+rt)). This skill provides a concrete application for the abstract algebraic concepts they are learning.