Mathematics in Grade 8
By grade 8, students are comfortable using numbers and understand the general principles behind what they do. They recognize that mathematics is important to their everyday life — especially solving problems that involve discounts, profits, and interest, as well as other skills they need to manage their money well. They also understand advanced concepts such as ratio and proportion, linear functions, and slope and its relationship to ratio.
Eighth-grade students use abstract thinking to solve algebraic expressions, including linear equations. They become skilled at statistical operations, such as analyzing data and sampling processes for possible bias and misleading conclusions.
TOPICS COVERED
Mathematics standards cover the following:
• Understanding numbers and how they work, such as adding, subtracting, multiplying, and dividing (Number Sense and Operations)
• Investigating patterns and using symbols (such as x + y = z) to analyze mathematical situations and change (Patterns, Relations, and Algebra)
• Identifying shapes, sizes, and relationships (Geometry)
• Using number relationships to find out size and volume (Measurement)
• Doing experiments, collecting data, and using the information to decide what will happen (Data Analysis, Statistics, and Probability)
WHAT YOUR CHILD SHOULD KNOW
BY THE END OF GRADE 8, YOUR CHILD SHOULD KNOW AND BE ABLE TO PERFORM THESE SKILLS:
1. Explain the properties of and compute with real numbers expressed in a variety of forms.
2. Read, write, and compare rational numbers in scientific notation (for example, 10² or 10¹). Use them in calculations and problem situations.
3. Solve problems involving ratio units such as miles per hour, dollars per pound, or persons per square mile.
4. Solve problems that involve markups, commissions, profits, and simple and compound interest.
5. Set up and solve linear equations with one or two variables using algebraic methods, models, and graphs. For example, as a salesperson you make $50 per week plus $3 per sale. You want to earn $100 per week. Write an inequality for the number of sales you need.
6. Demonstrate an understanding of the identity (–x)(–y) = xy. Use this identity to simplify algebraic expressions [for example, (–2)(–x+2) = 2x – 4].
7. Graph a linear equation using ordered pairs. For example, survey students at each grade level at your school, asking them how much time they spend on homework. Plot the grade level and time for each student as a point on a scatter diagram. Identify and represent the graphs of linear functions.
8. Use proportions to express relationships between corresponding parts of similar figures.
9. Recognize practices of collecting and displaying data that may bias the presentation or analysis.
HOME ACTIVITIES
1. Encourage your teen to learn and use correct mathematical terms. If these words (cube, square, perimeter, etc.) are new to you or others in your family, learn them together.
2. When you see an opinion poll reported in your newspaper, ask your young teen to find out some details of how the poll was taken. What makes a poll more accurate?
3. When you go out to eat as a family, ask your teen to calculate the tip. How much would the tip increase if everyone ordered dessert?
4. Have your teen make a project of drawing a scale model of a sports field or other landmark near your home.
5. Assess Your Child's Math Skills
Grade 8 Mathematics
Grade 8 Mathematics Sample Test and Think-Throughs