|
|
|
Printer Friendly Version
Investigation Question 2:
How can you tell air is "something?"
|
What To Do
|
|
Setting the
Scene
|
|
Remind students that in the last activity they found out that air affected
things (e.g., by pushing or filling them.) Ask the students to consider
other places where air can be found-other than around us in a room. Air
can be in things, like a cup or a box that would normally be considered
"empty". But if things with air in them are put in water, what
happens to the air?
Back To Top
|
|
Presenting the Investigation
Question
|
|
Introduce your students to the investigation question: "What
happens to the air in a container when it is put in water?"
Have your students discuss the question in pairs, then in groups, and then as a whole class. Record their answers on the flipchart.
Have your students brainstorm ideas about how this investigation question could be investigated.
- Design an experiment that could be used to test the investigation question.
- What materials would be needed?
- What would you have to do?
- What would be measured?
- How long would the experiment take?
Back To Top
|
|
Assessing What Your Students Already Know
|
|
Spend some time reviewing the results of Investigation 1 with your students.
They should now have at least a general understanding about air and how
it occupies the spaces between objects. Ask questions such as:
- What are some things that can hold air inside them?
- What are some things that air can escape from?
- Why can air escape from some things but not others?
Back To Top
|
|
Exploring the Concept
|
|
1.
|
|
Show your students the materials to be used in this investigation:
cotton balls, clear plastic drink cups, and clear glass or plastic
water container.
|
|
2.
|
|
Ask your students to predict what they think will happen if they
put the cotton balls in water and why? (They would get soaked!)
|
|
3.
|
|
Now ask them what will happen if the cotton balls are pressed down
into the bottom of the cup, and then the cup is put in water and
why? Have your students write down or draw their predictions along
with the reasons for them. (Some might answer that they would
still get soaked. Others might think that the cup would keep them
dry. Some might suggest that it would depend how the cup was placed
in the water.) Note: You may need to put a piece of tape across
the bottom of the cup to help hold the cotton balls in place, depending
on the size of the cup and the puffs.
|
|
4.
|
|
Ask for suggestions on how to lower the cup into the water so that
the puffs stay dry. Allow the students to write and draw pictures
to describe the various ways they could try to accomplish this.
|
|
5.
|
|
Have students experiment to test their predictions. (By experimenting
they will find that pushing the inverted drinking cup into the water
allows the cotton balls to stay dry. However, they may not be certain
of why this is so.)
|
|
6.
|
|
Have your students look again at the predictions they made. Ask
them to give explanations for what they have observed and whether
this fits or does not fit with their predictions. (Look for your
students to make the connection that air is trapped in the cup,
and that's why the cotton balls stay dry.)
|
|
7.
|
|
As a demonstration, use a sharp pencil to poke a hole in the bottom
of one plastic cup. Make sure the students see that there is a hole.
Ask them to predict what will happen if this cup is inverted in
water, just like the ones that kept the cotton balls dry. Go ahead
and invert this cup into a tank of water. The students will see
that the water rises in the cup, and they will see bubbles emerging
through the hole. Ask how this fit with their prediction. Discuss
how the hole allowed the air to escape, which allowed the water
to enter.
|
Back To Top
|
|
|
