What is Displacement? - Move Me Up!

Edwina Nelson Carter Elementary
5740 South Michigan
Chicago IL 60637
(312) 535-0860

State Goal:

Number 4 - As a result of their schooling, students will have a working
knowledge of the processes, techniques, methods, equipment and available
technology of science.

Objectives:

This activity is for all grades. Define displacement, volume, interpolation,
extrapolation, variable. Find the volume of an irregular solid.

Materials Needed:

6-50 ml graduated cylinders
water
marbles
pebbles
ice cubes
graph paper/data table
sharpened pencils
rulers

Strategy:

Working with a partner:

1. Pour 15 ml of water from the cup into the cylinder.
2. Carefully drop one of the marbles from the bag into the cylinder.
3. What is the level of the water in the cylinder now? Be sure and record
this information in the data area on the data table.
4. Carefully drop another marble into the cylinder. What is the level of the
water in the cylinder now?
5. Continue adding the rest of your marbles to the graduated cylinder and
recording the water level in the data area on the data table.
6. After you have added all 5 marbles and recorded the increase in water level
for each additional marble, graph the results of your investigation on the data
table.
7. Predict what the water level would be if you added a sixth marble.
8. Draw a picture of your experiment.

Now ask the students:

1. Why does the water level rise as a marble is added to the graduated
cylinder?
2. What was the volume of water in the graduated cylinder before you placed
any marbles in it?
3. Did the volume of the water change during the experiment? If it didn't,
then the volume of water is called a fixed variable. Can you think of any
other variables that were held fixed during the experiment?
4. Using your graph, predict the volume reading of the graduated cylinder if
there are: 2 marbles in the cylinder, 4 marbles in the cylinder, 6 marbles in
the cylinder.
5. If the water level reading of the graduated cylinder is 45 ml, how many
marbles are in the liquid? At 48 ml? At 50 ml?
6. Write the numbers which involved interpolation and those that involved
extrapolation.

Performance Assessment:

For the above questions, criteria used: Exceeds-5 to 6; Meets-4; Does not meet-
3 or below.

Scoring the data table: First examine the data table. If no information is
recorded, you must mark a zero in the box. If minimal data are recorded, you
must make a value judgment as to whether any of what is recorded would be useful
in understanding what the student did during the inquiry. If your answer is
"No", mark a zero; if your answer is "Yes", mark a one. If the information
is useful in describing what took place during the inquiry and if several
experimental points are recorded in some organized manner, mark a two. If the
student has additionally included some labels or appropriate units, mark a
three. Finally, if the appropriate units are in place and the student has
labeled the independent variable on the left and the dependent variable on the
bottom, mark a four.

Scoring the graph: Now examine the graph. If no information is recorded, mark
a zero in the box. If some minimal information is recorded, you must make a
value judgment as to whether or not what is recorded would be useful in
understanding what the student did during the inquiry. If your answer is "No",
mark a zero. If your answer is "Yes", mark a one. If the student has
plotted some data points from the above table and the plotted points show a
lower left to upper right pattern and has provided at least one label, mark
a two. If the student has all of the above and has provided the appropriate
labels for both axes and an acceptable title, mark a three.

For data table and graph, criteria used: Exceeds-6 to 7; Meets-5; Does not
meet-4 or below.

Conclusions:

The amount of water that an object replaces is called displacement. The volume
of water that an object displaces is equal to the volume of the object. The
volume of an irregularly shaped solid can be found by placing the object in
water and measuring the volume of water that the object displaces. If an object
displaces 10 ml of water, the object's volume is 10 ml.

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