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Investigation Question 2:
How warm or cool is it?
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What To Do
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Setting the Scene
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In the last investigation question students sequenced cups by relative
temperature. That works well as long as the cups with water to be compared
are very near each other. When comparisons have to be made less directly,
problems can arise. To illustrate this you can set three cups around the
room, each with a different temperature of water (each should be close
room temperature, only a little different from one another.) Have three
volunteers help you by standing at each cup. Tell them to sequence the
cups by temperature. Tell them to work together, but without moving. They
will find it very difficult, since each is unable to compare his cup with
the other two. In this case, descriptions do not work well. You can allow
the students to move around the room to the other cups, and still it will
be difficult to sequence the temperatures. Imagine if this were being
done at an even greater distance, such as if you were trying to describe
the temperature of the water in the cup to someone in another town (such
as for a recipe.) Describing temperature using numbers (i.e. measurements)
can help with this kind of communication.
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Presenting the Investigation
Question
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Introduce your students to the investigation question: "How can
we describe temperature using numbers?"
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?
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Assessing What Your Students Already Know
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From the preceding Temperature Investigation Question 1, your students
will know that a liquid can exist at different heat levels (i.e. temperatures)
and that this can be seen using a blank thermometer. It is also likely
that most students will have some idea of temperature measurement. They
will probably know that it feels hot outside when people say it is 90
degrees, or cold when the temperature is reported at several degrees below
zero. What they may not understand is just what a degree is in terms of
a measurement unit. They may also not know that there are two different
measurement scales, English (Fahrenheit) and metric (Celsius or Centigrade),
and that the metric, or Centigrade, is the scale conventionally used in
science.
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Exploring the Concept
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- Set up cups with three temperatures of water as you did for Temperature
Investigation Question 1. Give students the calibrated thermometers.
Have them repeat the insertions into the three cups as they did in Temperature
Investigation Question 1, but this time help them to read and record
the different temperatures in both degrees Fahrenheit and degrees Centigrade.
As they did before, they can determine the sequence of the cups based
on temperature, but this time using measurements instead of a relative
scale. To do this they can construct a chart like the one below, or
a computer version (Your students should learn that it is important
in science to use tools, such as computers and calculators, observational
procedures and recording techniques such as tables):
- Now have your students look closely at two measurements, °F and
°C. Ask them to note and discuss the differences (This is a good
opportunity to introduce the idea that for a unit of measurement to
work, a group of people have to all agree to use it. The Fahrenheit
and Celsius scales are usually included on thermometers because each
is used by different groups - Fahrenheit, which is an older traditional
measure, is used in the United States, Celsius, which is newer, is used
in most other countries in the world. Celsius is also the unit mostly
used by scientists.)
- Provide a cup D (with a lid if possible) with water within the range
of the temperatures of cups A through D, and have the students again
add it to the sequence, but this time using the temperature measurement
of the water in the cup. Do all the groups have water the same temperature
in the cup marked D? How does measuring make it easier to answer that
than it was in Temperature Investigation Question 1 with just relative
comparisons to use?
- Get your students to think about air and how it is often cooler at
some times, or in some places, than others. Let them see what the temperature
is in the classroom. (You can ask different students in different
parts of the room call out their observed temperatures to see if they
are the same or different in one area of the room and another. Students
near a window or an air vent may find that their measurements are several
degrees above or below those of other groups.)
- If the outside air is quite different to the classroom temperature
(hot or cold day) have your students go outside to measure and record
the air temperature. (This is an opportunity to help your students
begin to understand that the temperature of air is an important part
of "weather". Again, as in the classroom, different locations
may provide different temperature readings depending on specific conditions.)
- Tell the students that it will be their job to record the outdoor
temperature daily for ten school days. They will need to do this in
order to describe current weather conditions throughout the period.
They will also record other factors to describe the conditions and to
compare one day to the others. (Your students should devise a good
way of recording this information. Help them to design an appropriate
chart, computer data program, or other method.)
- Ask the students why it will be important to record the temperature
in the same location and at the same time each day. (Even young children
will see the need for such controls in keeping records. You might reinforce
this by asking if it would be fair to measure the temperature at different
times of day as they compare one day's conditions to the next.)
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