Understand Relative Sizes of Measurement Units

Students learn that measurement units within the same system have different sizes relative to each other (e.g., a kilometer is larger than a meter; a pound is larger than an ounce). Students compare units and identify which is larger or smaller within customary and metric systems for length, mass/weight, capacity, and time.

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Grade 4 · Measurement Units & Conversions · question 1 of 3

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20 rungs. A star at the top.

What is the jug's reading in liters?

Your answer:L

How it is taught

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Units in one system come in different sizes.

A pound holds many ounces.

Read it: Every row is the same times

1 foot is 12 inches, 2 feet are 24 inches and 3 feet are 36 inches. Every row of the table is times 12, so 4 feet are 4 × 12 = 48 inches.

Find how many small units make 1 big unit: 1 foot is 12 inches.
From the big unit to the small one there are more of them: multiply by 12.
From the small unit to the big one there are fewer: 72 inches ÷ 12 = 6 feet.

A foot is longer than an inch, so it takes 12 inches to make the same length as 1 foot.

Each foot more adds 12 inches more, so every row of the table grows by 12.

The table works both ways: read down to multiply, and read up to divide.

Multiply by the factor to change to the smaller unit, and divide by it to change to the bigger unit.

Adding 12 instead of multiplying, and saying 4 feet are 16 inches.

Every foot is 12 inches, so 4 feet are 4 groups of 12: 48 inches.

500 centimeters = ___ meters — 5. 100 centimeters make 1 meter, so 500 of them make 500 ÷ 100: 5.

1 km vs 1 m vs 1 cm

We measure tiny things and huge things — but not with the same unit. Let's see why.

A meter is about the size of a baseball bat. We write it with the letter m.

A kilometer is much longer — it takes about ten minutes to walk one! We write it as k m.

Look how much bigger one kilometer is than one meter.

Exactly how many meters fit inside one kilometer?

Let's split the kilometer into ten equal pieces. Each piece is one hundred meters.

Ten groups of one hundred make one thousand! One kilometer equals one thousand meters.

Now what's smaller than a meter? A centimeter — about the width of your fingernail.

One meter equals one hundred centimeters.

The bigger the unit, the fewer we need. Kilometers for long roads, meters for rooms, centimeters for small things.

Grade 4 · Comparing metric length units

What you see

While they climb, your page writes one true line to ask about tonight, and a short note each Sunday.

MayaGrade 3 · Mathematics

Did you know?

A chessboard has 64 squares — share them out between the 8 rows and each row holds exactly 8.

Today’s goal: 1 star — one skill mastered, every rung of its ladder climbed
Climbing now: Divide within 100

An example student.

MayaGrade 3 · Mathematics

Maya earned 2 stars this week — Interpret multiplication as equal groups, which took 6 answers over 3 days before its star landed 3 days ago and Multiply by 6, 7, 8 and 9. Next up: Divide within 100.

An example week.

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