Metric Measurement (mass/weight)
Introduction: How can you figure out how much of your pencil gets “eaten” by a pencil
sharpener each time you sharpen a pencil? How can you figure out how large a gulp of
water is?
Objective: In this activity, we will become familiar with the parts of a triple-beam
balance that is used to measure mass, and we will practice measuring the mass of
different objects. Following this, we will learn how to “weigh-by-difference” to find the
mass of different objects.
Weigh pan
pointer
Dial-O-Gram
Procedure: To “Zero a Balance”
1. Remove the rubber stopper from the balance.
2. Check to make sure that the balance is clean. Wipe and clean it if
necessary
3. Move the two weights to the left of the balance (next to the weigh
pan).
4. Make sure the Dial-O-Gram is set at zero.
5. Look to see if the pointer line is perfectly in line with the mark on the
post. This indicates whether the balance is zeroed.
6. If the lines still do not meet, raise your hand so that Mr. Bendele or
Mr. Thompson can help you.
To Weigh Objects
1. Make sure the rubber stopper is removed from the balance.
2. Use the following steps to weigh each object listed in the chart (in
grams), and record its weight in the chart.
3. Make sure the balance is zeroed and the weigh pan is clean.
4. Place an object on the weigh pan.
5. Move the weights and Dial-O-Gram until the pointer just balances at
the white mark on the post. Do this by first moving the large weight to
the right. If it is too heavy to balance the object, move it back to the
left and try the next smaller weight. Continue going smaller by using
the Dial-O-Gram until the lines match up. Make sure that the two
moveable weights fall into notches as you move them on the beams.
6. Weights/Dial-O-Gram can be measured as accurately as the nearest
tenth of a gram by positioning the Dial-O-Gram.
7. One the weights/Dial-O-Gram have been positioned so that the beam
pointer aligns with the mark on the post, add each of the marked
weights and Dial-O-Gram together to get a total.
8. Record the total mass in the chart below under “Weight”. Make sure
you include the correct unit.
9. Before you are done with the balance, make sure it is clean, all weights
and dials are set at zero, and the rubber stopper is back in place.
Object
test tube
pink scissors
Sierra Mist cup
one penny
marble
popsicle stick
cork
science book
cut off bolt
straw
paper clip
aluminum cube
mirror
cut off nail
test tube rack
dissecting pan
ruler
Weight (in
grams)
Weight (in mg)
Weight (in kg)
plastic mason jar
25mL graduated
cylinder
100mL
graduated
cylinder
250mL beaker
beaker brush
large pipette
small pipette
tongs
hot hands
flower pot
50mL beaker
pop can
Questions: Answer each of the following questions using at least two
complete sentences.
1. Why is it important to make sure that the weigh pan is clean before
weighing objects?
2. Explain the difference between grams, milligrams, and kilograms.
When and why would you use each unit?