🔢 MathGrade 4Lesson 31
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Convert Metric Units
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Learning Objectives
- 1Identify and use metric units for length, mass, and capacity
- 2Convert between metric units using multiplication and division
- 3Apply metric conversions to real-life measurement problems
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Mini Lesson
Metric units are based on powers of 10. The prefix kilo- means multiply by 1000, centi- means divide by 100, and milli- means divide by 1000. Knowing the prefixes lets you convert any metric measurement quickly.
Length: km, m, cm, mm
- 1 km = 1000 m — multiply by 1000 to go from km to m.
- 1 m = 100 cm — multiply by 100 to go from m to cm.
- 1 cm = 10 mm — multiply by 10 to go from cm to mm.
- To convert the other way, divide: 500 cm = 500 ÷ 100 = 5 m.
Mass: kg and g
- 1 kg = 1000 g — multiply by 1000 to go from kg to g.
- To convert g to kg, divide by 1000: 3000 g = 3 kg.
Capacity: L and mL
- 1 L = 1000 mL — multiply by 1000 to go from L to mL.
- To convert mL to L, divide by 1000: 4000 mL = 4 L.
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Tip: to convert to a smaller unit, multiply. To convert to a larger unit, divide. Ask yourself: "Am I going to a smaller or larger unit?"
Vocabulary
metric system
A measurement system based on powers of 10.e.g. Most of the world uses the metric system.
kilo-
A prefix that means one thousand (×1000).e.g. 1 kilometer = 1000 meters.
centi-
A prefix that means one hundredth (÷100 of the base unit).e.g. 1 meter = 100 centimeters.
milli-
A prefix that means one thousandth (÷1000 of the base unit).e.g. 1 liter = 1000 milliliters.
mass
How much matter is in an object, measured in grams or kilograms.e.g. A bag of sugar has a mass of 1 kg.
capacity
How much liquid a container can hold, measured in liters or milliliters.e.g. A water bottle has a capacity of 500 mL.
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