Grade 8 · The Number System

8.NS.A.1

Know that numbers that are not rational are called irrational. Understand informally that every number has a decimal expansion; for rational numbers show that the decimal expansion repeats eventually, and convert a decimal expansion which repeats eventually into a rational number.

Cluster 8.NS.AKnow that there are numbers that are not rational, and approximate them by rational numbers.

Where this sits in the school year

Our Grade 8 Math scope and sequence teaches 8.NS.A.1 in Unit 8: Roots & Irrational Numbers, weeks 23–24.

Introduce square and cube roots as inverse operations, and place irrational numbers on the number line. See the full pacing guide →

Builds on

Suggested prerequisites. This sequencing is our editorial guidance, not part of the Common Core.

7.NS.A.2.d

Teaching Kits for this standard

🔍 Hunting for Irrational Numbers60 min · Number line investigation

Browse the library filtered to 8.NS.A.1 →