Probe Pocket Thermometer

The probe pocket thermometer is a battery-operated thermometer.  It can be used inside or outside in temperatures ?58 degrees F to 500 degrees F.  The stainless steel probe can, therefore, be inserted into almost any substance.  It can be used to measure soil temperatures at various times of the year.  It can also be used to measure heated substances.  The thermometer consists of a temperature sensitive stainless steel probe and a head that holds a CPU microprocessor unit.   It can measure in Fahrenheit and Celsius degrees.  When it is being carried or is sitting in the "on" mode, it measures the ambient temperature.  It also has maximum/minimum capacity.

Students will be able to use a probe thermometer to measure the temperature of the soil and other substances, understanding that the sun and climate are primary forces in changing the temperature of the land and water of the earth.

Instructions for Set Up
The probe thermometer should come ready for use.  To use, press the "on" button quickly and release.  The immediate reading will be of the ambient temperature.  Insert the probe into the substance.  The head will display the probe temperature every 10 seconds.  It is best to read while the probe is still in the substance.  Ambient air will immediately affect the reading as the probe is withdrawn.  The "off" button is pressed once for turning off the thermometer in 6 to 7 minutes and pressed twice for instant off.  On the side of the head there is a small slide switch that will allow the user to change the scale from Fahrenheit to Celsius.  One 1.5 v (watch) battery runs the entire unit.  The battery case is opened with a coin.

Probe Pocket Thermometer
Activity: The Sun Heats the Earth

Objective:  Students will be able to measure a variety of substances using a probe thermometer accurately.  They will be able to turn the thermometer on and read the display.
Probe Pocket Thermometer
Area of unfrozen soil
For procedure 2:  2 large containers such as 2 gallon     milk jugs with about the top third cut off.  One filled with soil and one with water.

Time:  45 minutes
Background Information:
The probe of the thermometer measures the ambient temperature of whatever it is in.  The sun heats the earth and causes changes in the land and water of the earth.  These temperatures are important for many reasons such as growing crops, polar melting, water evaporation and the water cycle, the survival of living things on the earth.

Procedure 1:
Assign students to find out what the low temperature was the night before this lesson.  Also, have them check an outside thermometer at the time of the lesson.  Note these two temperatures as you discuss the sunÝs role in warming the earth and the earthÝs water.  Have the students predict what the think the temperature of the soil might be.  Ask a number of the students what the reasons are for their predictions.  Show the group the probe pocket thermometer, letting them see how to turn it on.  Demonstrate how it measures the ambient air around the probe by letting them read it being held by its head and then with a hand around the probe.
    When students are fairly sure of the operation of the probe thermometer, have the group move to the outside where they can place the probe in the soil.  What is the temperature of the soil?  Is it warmer, colder, or the same as the air temperature?  Is it the same in all areas of the soil?
    When students return to the classroom, discuss the soil temperature and why it is so.  What season is it?  Have the previous days been cold or hot?  What time of the day is it?  Would the temperature be different first thing in the morning or late in the afternoon?   What temperature does the soil need to be for most vegetable crops to grow?  If the students have studied molecules, the concept of temperature and mass ties in well.

Have students measure soil temperature in the same place first thing in the morning and well into the mid-afternoon.  Does it change?  Why or why not?

Procedure 2:
This lesson can be used to extend the previous lesson or in place of it.  It adds the temperature of water to the data.
    Set one large container of soil and one of water in an accessible place outside.  Repeat the introduction of the probe and the discussion of procedure 1.  Have the students measure the soil and the water temperatures as early in the day as they arrive and at intervals of 2 hours.
    Have them record the information on the recording sheet.  Meet to discuss their findings.  Why are the changes in water greater than those in soil?  When was the water the warmest and the coldest?  When was the soil the warmest and the coldest?  The temperatures may be plotted to show the visual affect of the sun on the earth.

Probe Pocket Thermometer
Recording Sheet
Name:  ____________________


  Time                      Temperature


  Time   Temperature

Soil coldest at__________      Warmest at ____________

Water coldest at ________    Warmest at_____________
 Barometer  Rain Gauge  Hygrometer  Anemometer

This curiculum project was funded by the Colby Partnership for Science Education, the Howard Hughes
Medical Institute, and the Bell AtlanticFoundation.