CurriculumGrade 9Mathematics

Units and Scale

Aligned to N-Q.A.1 — Common Core State Standards for Mathematics.

What this lesson teaches

Units tell you what a number means and how quantities combine; carry them through every step and cancel them like factors. On a graph, the scale and origin decide how large or steep the data appears.

Worked example

A car travels 150 miles in 3 hours. Divide to find the rate: 150 miles / 3 hours = 50 miles/hour. The units mi/h confirm the result is a speed.

Practice questions

  1. A recipe uses 2 cups of flour for 12 cookies. Find cups per cookie.
  2. Convert 90 km/h to kilometers per minute.
  3. A graph's y-axis starts at 50 instead of 0. Explain how that could make a small change look large.

Watch the lesson

Every lesson comes with a video taught in English and Spanish — the same video the QR code in the printed workbook opens.

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En español

Unidades y Escala

Las unidades te dicen qué significa un número y cómo se combinan las cantidades; llévalas en cada paso y cancélalas como factores. En una gráfica, la escala y el origen deciden qué tan grande o inclinado se ve el dato.

Ejemplo: Un carro recorre 150 millas en 3 horas. Divide para hallar la razón: 150 millas / 3 horas = 50 millas/hora. Las unidades mi/h confirman que el resultado es una rapidez.

More Number & Quantity lessons

Rational ExponentsN-RN.A.1Radicals and Rational ExponentsN-RN.A.2Rational and Irrational NumbersN-RN.B.3Choosing Quantities to ModelN-Q.A.2Accuracy and PrecisionN-Q.A.3

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