Mathematics Measurement: Lesson 3 - Grade 8 (Page 2 of 9) in pdf

Mathematics Measurement: Lesson 3 - Grade 8 Page 2

Lesson 3: Measurement

Say:

Let’s talk about weight. When might you need to measure weight?

(when buying fruits and vegetables, to make a sports team, to ship

something by mail) What kind of tool would you use to measure weight?

(scales) You will see both the terms weight and mass. Mass is the amount

of matter in an object. Weight is a measure of how heavy an object is.

Customary units are used to measure weight. Metric units are used to

measure mass. Do not make a big deal of this difference. What units do

you use to measure weight/mass? (pound, ounce, ton, gram, kilogram,

milligram) There are others, but these are the most common ones.

þ Write customary and metric on a piece of paper or on the board. Divide

the units into customary and metric units.

Customary

Metric

Pound, ounce, ton

gram, kilogram, milligram

Say:

Let’s put the units in order from the smallest to the largest in each

system. Write the symbol next to the unit.

Customary

Metric

ounce (oz)

milligram (mg)

pound (lb)

gram (g)

ton (T)

kilogram (kg)

Say:

Let’s start with the customary system. Can you think of something that

weighs about a ounce? (a slice of bread); Something that weighs about a

pound? (a loaf of bread); About a ton? (a small car.)

What units would you use to measure the following items?

A. The weight of a grown dog (pounds)

B. The weight of a elephant (tons)

C. The weight of a computer (pounds)

D. The weight of a potato (ounces)

E. The weight of a sack of potatoes (pounds)

F. The weight of a paper clip (ounces)

þ Find an object that weighs about one pound and some other objects that

weigh more or less than a pound. (You need to weigh these objects ahead of

Grade 8 Mathematics

Lesson 3, Measurement

Mathematics Measurement: Lesson 3 - Grade 8 Page 2