Sink or Float
Objective: Students will experiment with different liquids and materials to investigate
the concept of density.
Physical Science 1e Students know matter has three forms: solid, liquid, and gas.
Salad oil (olive or sesame oil works best)
Tall glass of clear water, no ice
at least 7 small clear plastic cups
light corn syrup
a piece of cork
a piece of a candle
a piece of metal
*Each object should also be the same size as each other.
Computer with internet access
1. Demonstrate to the whole class using the following procedures (taken from
Fill the glass about ¾ full with cold water.
Slowly pour some oil into the glass. Stop pouring when you have a layer
of oil about 1/2 inch or 1 cm thick on the water's surface.
Have students talk with each other and write down what they think is
happening and why.
Next, generously sprinkle salt on top of the oil and watch what happens.
Again, have students discuss and record their thinking and explanation of
what they think is happening and why.
Add more salt or any other condiment to see what else might happen.
2. Once students are done observing and discussing what they think is happening,
have students write a few questions about what they just observed.
3. Put students in small groups of about 4 students.
4. Teacher can either write the following procedures for the small group experiment
on the board for everyone to see or typed and printed them to hand out to each
group (taken from http://www.canteach.ca/elementary/physical8.html).
Pour liquids in each glass in the order shown below. Pour out a glass of each
liquid combination, so you will have 3 filled glasses in total.
1) 2) 3)
corn syrup milk oil
milk oil corn syrup
oil corn syrup milk
What happened? Draw your observations. Why did this happen?
Try the experiment with other liquids.
Pour out a little of each liquid in seperate glasses. Include a glass with a little
water in it. So, you will have 4 glasses of liquids in total.
Try dropping a piece of cork, into the middle of each liquid. In which liquids did
it sink? In which liquids did it float? Record.
Fish out the cork, or use a new piece that is equal in size and weight, and repeat
the process with the pieces of candle and metal.
Which objects floated the most? Which objects sank the most? Organize the
objects for most to least dense.
Try the experiment with other liquids.
5. Introduce the concept of “density” to students. Explain what it is and how it
Density resources for teachers:
6. Explain and discuss with students what happen with the liquids in part 1 of their
experiment in terms of density. Which liquid is less or more dense? Why? How
do they know this? Have students organize the liquids from least to most dense.
7. The same can be done for part 2 of the experiment.
8. Have students work in their small groups to explain, on their own, what happened
in the demonstration in the beginning of this lesson with the water, salt, and oil.
Write or draw and label their ideas and explanations on a piece of paper or in their
9. Have students go to a computer lab to work individually or in small groups. Have
students go to http://www.seed.slb.com/en/scictr/lab/buoy_exp/index.htm
10. Students will engage in an virtual experiment to investigate buoyancy.
11. After the virtual experiment, they can learn more about buoyancy by clicking on
the links and read more about it.
12. Discuss with students what they know about buoyancy and density. Have them
define these terms using their own words and examples using their notes and
observations during previous activities.
Objective: Students will observe, track, and record the different phases of the moon over
a period of time.
Earth Science 4b Students know the way in which the Moon’s appearance
changes during the four-week lunar cycle.
Phases of the Moon applet
Charting the Moon worksheet
Phases of the Moon worksheet
Styrofoam ball (2" to 3" across)
Pen or small stick
The Moon is only visible at night time; it is not “up” during the day
Earth’s shadow causes phases of the Moon
Clouds cause the phases of the Moon
Earth has few impact craters because the Moon protects it
The moon does not rotate on its axis as it revolves around the earth.
The phases of the moon are caused by shadows cast on its surface by
other objects in the solar system.
The shape of the moon always appears the same.
There is a side of the moon that is always dark.
1. Have your students place the styrofoam ball on the pen or small stick. This ball
represents the moon. Have them hold the ball so the light shines on it. Light is shining on
how much of the ball?
Half of the ball is lit up.
If the ball is held in a different place, is more, less, or the same amount of it covered with
Regardless of where the ball is held, half of it is always light.
2. Now have them face the sun and hold the ball in front of them. As they look at the ball
do they see any of the light that is falling on it?
They should not see any of the light falling on the ball. Why don't they see light falling
The half of the ball that is lit is facing away from them.
3. Have them move the ball slowly to their left (counterclockwise). What begins to
They should begin to see part of the ball's lighted half.
4. How far must the ball be moved before half of the lighted side is visible?
The ball must be moved one-quarter of the way around their head.
Before all of the lighted side is visible?
5. What happens if you keep moving the ball in the same direction?
They begin to see less and less of the lighted half of the ball.
6. The bright light represents the sun and the styrofoam ball represents the moon. As the
moon revolves around Earth we see different amounts of its sun lit half. This causes
the phases of the moon! Where is the moon in its orbit at:
a crescent? About one-eighth of the way around
first quarter? One-fourth of the way around
full moon? Half way around
third quarter? Three-quarters of the way around
new moon? Directly between the Sun and Earth at the beginning of the cycle
Procedure / Discussion Questions
Location of the Moon
The position of the moon in our sky at different phases can be demonstrated. The position
of the sun and Earth will first be used to establish directions.
1. Have your students stand facing the sun (bright light). What time of day does this
Since they are facing the sun, the sun is overhead in the sky. Thus it is noon.
What direction are they facing?
2. Which direction is to their left? East
to their right? West
3. Now have them turn so the sun sets. In which direction did they have to turn (left to
right or right to left)?
In order to have the sun set in the western part of the sky, the students will have to turn to
4. What time is it when the sun is:
directly to their right? Sunset
directly to their left? Sunrise
directly behind them? Midnight
5. To get some idea of where the moon is in the sky at different phases have the students
turn so the sun is setting.
What direction are they facing? They are facing south.
Left and right are what directions? Left is east and right is west.
6. Now have them hold the moon so that it is in the same direction as the sun. This is the
new moon phase since the sun lit half of the moon is facing away from us. Now have
them move the moon in its orbit (to the left).
They begin to see part of the lighted half of the ball -- a crescent moon.
7. In what direction should they look to see the crescent moon at sunset?
8. Have the students move the moon so it is in front of them.
What phase is this? First Quarter
In what direction is the moon? Due south
9. Have the students continue until they reach full moon.
In which direction should they look for a full moon?
In the east
What happens if they move the moon further in its orbit?
It can no longer be seen.
When should they look for it?
They must look for it later than sunset.
10. Repeat the above procedure, except have the students turn so the sun is rising.
What direction are they facing now? South
What directions are right and left? Left is east and right is west.
Where should they put the moon in its orbit so that it is full? On the opposite side of the
sun, in the west.
Have them slowly move the moon in its orbit. How does the phase and position change?
As the moon moves toward the east, the students will see less of the sunlight half.
Why is this different from before?
Before they were seeing more and more of the sunlit half as the moon moved from the
west to east and now they will see less and less.
Have students track the moon phases for two weeks using the Charting the Moon
Have students use the http://aa.usno.navy.mil/data/docs/RS_OneDay.php