20.2 Compare Metric Units of Length

20.2 Compare Metric Units of Length

4.MD.A.1: Know relative sizes of measurement units within one system of units including km, m, cm, mm; kg, g; lb, oz.; l, ml; hr, min, sec.

Objective

I can represent and compare measurements given in different metric units of length.

Multiple Choice

Rachel has a large pot for cooking. Which metric unit of measurement would be best for measuring the liquid volume of the pot?

• meters

• liters

• grams

Before we begin, let's remember what we learned yesterday:

• Meters have to do with length

• Grams have to do with mass

• Liters have to do with liquid

• We will mostly be using the prefixes deci- (1/10th), centi- (1/100th), milli-(1/1,000th), and kilo- (1000).

• Our prefixes change our bases by multiples of ten.

Open Ended

An ant is about 1 centimeter long. This sidewalk square is about 1 meter long. How do these lengths compare?

So what can we learn from this picture?

• The ant is a centimeter long

• The sidewalk is 1 meter long

• This is a visual representation of how 1 centimeter is a small part of a meter.

• A centimeter is a meter divided by 100.

Vocabulary reminder

A decimeter (dm) is a metric unit for measuring length or distance. 10 centimeters are equal to 1 decimeter. 10 decimeters are equal to 1 meter.

Open Ended

Ada builds a structure that is 1 meter tall. Her little sister, Diana, builds a structure that is 1 decimeter tall. How could you compare the heights?

So what did we learn?

There are 10 decimeters in 1 meter. It takes 10 of Diana's 1-decimeter structures to equal the height of Ada's 1-meter structure.

Also, I know this picture is blurry, but I needed you to see how the small structure is 1/10th of the big one.

Vocabulary Reminder

10 millimeters (mm) are equal to 1 centimeter.

Our next problem will focus on the following picture:

How does the width of the heads of 5 thumbtacks set end to end compare to the width of the heads of 55 pins set end to end?

How can we compare centimeters and millimeters?

There are 10 millimeters in 1 centimeter. Multiply 10, the number of millimeters in 1 centimeter, by the number of centimeters to find the number of millimeters.

Multiple Choice

So if each thumb tack is one centimeter long, and each pin is one millimeter long, fill in the blank:

The width of the heads of 5 thumbtacks is ________ the width of the heads of 55 pins.

• greater than

• less than

• equal to