---
title: "Converting measurement units (age 9+)"
description: "Know relative sizes of measurement units within one system (km/m/cm/mm, kg/g, l/ml, hr/min/sec); convert between different metric units and express measurements in terms of a smaller unit; record equi"
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source: https://lightmysky.com/learn/mathematics/converting-measurement-units-age-9-mt_Zks8xyInSG.md
retrieved: 2026-10-19
---

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# Converting measurement units (age 9+)

Know relative sizes of measurement units within one system (km/m/cm/mm, kg/g, l/ml, hr/min/sec); convert between different metric units and express measurements in terms of a smaller unit; record equivalents in conversion tables

Subject: Mathematics · Area: Measurement · Ages 9 to 10
Page: https://lightmysky.com/learn/mathematics/converting-measurement-units-age-9-mt_Zks8xyInSG

## Ready when they can

- Convert 3.5 km to 3,500 m
- Complete a conversion table for cm and mm: (1,10), (2,20), (3,30)...
- Express 2 kg 350 g as 2,350 g

## Lesson: Turning big units into small ones

You already know how to change between measurement units. Now you'll work with bigger numbers and decimals, and combine two units into one, like turning 2 kilograms 350 grams into a single number of grams.

To turn a bigger unit into a smaller one, multiply. A kilometer is 1,000 meters, so 3.5 km becomes 3.5 times 1,000, which is 3,500 m. The same rule works for kg to g and l to ml. For cm to mm, multiply by 10 instead.

*(drawing: Each cm equals 10 mm. What number completes the pattern for 4 cm?)*

**Example.** A bag of flour weighs 2 kg 350 g. To write it only in grams, change the 2 kg to 2,000 g, then add the extra 350 g. 2,000 plus 350 makes 2,350 g.

**Tip.** Watch your zeros. Multiplying by 1,000 adds three zeros (or moves the decimal point three places right). Multiplying by 10 moves it just one place.

**Recap.** To change to a smaller unit, multiply by 10, 100, or 1,000, then add on any extra amount carefully.

## Practice

18 questions on this page, each with its working shown.

## Needs first

- [Converting measurement units](https://lightmysky.com/learn/mathematics/converting-measurement-units-mt_d8al9JcajP)
- [Multiplying and dividing by 10, 100, and 1000](https://lightmysky.com/learn/mathematics/multiplying-and-dividing-by-10-100-and-1000-mt_LlMl2PbaZe)

## Opens up

- [Converting units with decimal notation](https://lightmysky.com/learn/mathematics/converting-units-with-decimal-notation-mt_2VpdPjvewx)
- [Measure word problems with fractions and decimals](https://lightmysky.com/learn/mathematics/measure-word-problems-with-fractions-and-decimals-mt_5HV4mbgSGH)
- [Metric & Imperial Conversion](https://lightmysky.com/learn/mathematics/metric-and-imperial-conversion-mt_p6MhZJYYPN)
- [Scientific Quantities and Units](https://lightmysky.com/learn/science/scientific-quantities-and-units-mt_vdHqdaflog)