Earth Science Learning Community

Lesson 2 - Bring on the "HEAT"!

Lesson Plan

fire

State Standards:

Grades 6-8 Earth and Space Science: Heat Transfer in the Earth System

#3. Differentiate among radiation, conduction, and convection, the three mechanisms by which heat is transferred through the Earth's system.

#4. Explain the relationship among the energy provided by the sun, the global patterns of atmospheric movement, and the temperature differences among water, land and atmosphere.

Essential Question:

How does the light from the Sun produce the energy that sustains all living things on Earth?

Lesson Question:

What are the three mechanisms that transfer heat:
Radiation, Conduction, Convection?
How are each of these mechanisms different from each other?
How do these mechanisms affect materials that vary in color and texture?

Introduction:

You will be researching the three ways that heat can move either within a material or between different materials. A lab investigation will explore how different properties of these materials can affect the transfer of heat. With this understanding, you will review the problem that a local farmer is having getting his vegetables safely to market and propose a solution to keep his vegetables fresh during shipping.

 

Task:

Observe a demonstration of heat and its different effect on a balloon filled with air and a balloon filled with water. Write your Prediction and Explanation prior to demonstration and then write your Observation and Explanation after viewing the demonstration.

Lesson Experiences:

Lesson #1

Elicit: Warm-Up Question

On a sunny summer day, why do you think you can comfortably walk barefoot on the green grass, but not on the black parking lot pavement? Write down your answer and then share it with the person at your table.

Engage: Observe a demonstration of heat and its different effect on a balloon filled with air and a balloon filled with water. Write your Prediction and Explanation prior to demonstration and then write your Observation and Explanation after viewing the demonstration.

Demonstration

Your teacher has a balloon filled with air and I have a lit candle. What do you ‘predict' will happen when I place this balloon in the flame of the candle? Write your prediction and write an explanation for what you think will happen.

Now, write down what you observed and whether this is what you predicted. Write an explanation for what you observed.

Next, your teacher has a balloon filled with water and the lit candle. What do you ‘predict' will happen when I place this balloon in the flame of the candle? Write your prediction and write an explanation for what you think will happen.

Now, write down what you observed and whether this is what you predicted. Write an explanation for what you observed.

What was your observation in the first trial? … in the second?

Can we all agree that the candle caused the balloon to burst in the first, but failed to burst the balloon in the second? Why? How can we explain this difference?

Let's explore how energy from light (radiation) effects the heating of different materials.


Explore: You will work in groups of four with each student having an assigned role: Getter, Task Master, Recorder, Reporter.

Go to this website http://www.ucar.edu/learn/1_1_2_5t.htm .
Read the background on Heat Transfer, then perform the activity.

Materials

Procedure

  1. Fill the pie pans to the same level, one with dark soil, one with light sand, and one with water.
  2. Place the pie pans on a table or desk and position the lamp about 12 inches above them.
  3. Place a thermometer into each pie pan, securing it so it measures the temperature just under the surface of the substance in the pan.
  4. Record the starting temperatures in the Heating Cycle table.
  5. Turn on the lamp and record the temperature of each substance every minute for ten minutes.
  6. At the end of ten minutes, turn the lamp off.
  7. Continue to record temperatures for each substance every minute for ten minutes in the Cooling Cycle table.


Note: Feel free to vary the materials in the pie pans. Use different colored soils, dry and wet soils, grass, green or dry leaves, or different types of coverings such as plastic or aluminum foil. Use your imagination to design and conduct your own research into the influence of surfaces on temperature.

Heating Cycle

Surface Material

Start Time

Start Temp

Temperature Each Minute

1

2

3

4

5

6

7

8

9

10

 

Cooling Cycle

Surface Material

Start Time

Start Temp

Temperature Each Minute

1

2

3

4

5

6

7

8

9

10

Evaluate: Observations and Questions

  1. Using the data tables, graph the heating and cooling cycles to compare the rates at which the various substances heated and cooled.
  2. Which material absorbed more heat in the first ten minutes?
  3. Which material lost the most heat in the last ten minutes?


sunlight on water

Elaborate:

1. Imagine that it's summer and that the sun is shining on the ocean and on a stretch of land. Which will heat up more during the day? Which will cool more slowly at night? Explain.

2. Imagine three cities in the desert, all at about the same altitude and latitude.

Which city would likely have the highest average summer air temperature and why?

3. The earth's surface tends to lose heat in winter. Which of the above cities would have the warmest average winter temperature? Why?

4. Since the sun is approximately 93 million miles from the earth and space has no temperature, how do we get heat from the sun?

5. How would the uneven energy absorption by different surfaces on earth (water, soil, snow, trees, sand, etc.) affect the atmosphere?

Explain: Let's look at heat and the different ways that heat is able to move between things and within a single thing like a liquid or a gas.

Evaluate: Your teacher will project a picture on the screen.

Decide which heat transfer type is pictured then put you head down with eyes closed and raise your hand with the number of fingers to indicate which heat transfer is represented

Use this finger key on the board if you forget.

Lesson #2

Elicit: Try this warm-up question -- How does uneven energy absorption by different surfaces on Earth affect the atmosphere?

Using the Claim, Evidence, Reasoning format write your explanation why the different materials (dark soil, light soil, and water) responded to heat the way that they did given the results that you recorded from the previous Lab activity.

Engage and Explain: Many of you had difficulty with Question #8 from the Lab yesterday. Let's watch the Bill Nye video on “Heat” (18 min.) and see if this doesn't clarify the question:

How does uneven energy absorption by different surfaces on Earth affect the atmosphere?

This will also provide some helpful review of our earlier definitions of heat and temperature as well as see models of air convections. Please answer the questions on the handout while you watch the video.

Video handout

Note: The video presents these concepts more fully than a brief clip. This video includes a strong visual model of air convection in a chamber when air in the chamber is warmed by a lamp source and cooled air is introduced to replace the rising warm air simulating air currents.

video link

Extend and Evaluate: What are the processes that create the local winds that we often feel in the summer when we are at the seashore? Refer to your lab results on the differential heating of materials. Consider how these materials heat up at different rates and what effects this heating may produce when the sun is out during the day and when the sun has set at night.

Diagram how you predict air would flow in these two scenarios on the blank handout provided.

Check your prediction with the diagram that I am projecting on the board. Thumbs up if your prediction is similar to this diagram, thumbs down if your prediction was different.

Lesson #3

I. General Context Statement

We have seen how heat can transfer by conduction, convection and radiation.

Our experience on Earth includes these transfers with energy from the Sun arriving by radiation and exciting the molecules of gases in our atmosphere. Some radiation reaches Earth's surface and causes molecules in the land and water to vibrate, producing heat energy which can transfer by conduction to adjacent materials.

In fluids, this heat energy can transfer as gas or liquid molecules move faster and farther reducing the density of the fluid. This reduced density allows the cooler, more dense molecules to displace the warm molecules causing them to rise and create convection loops circulating gas or liquid currents. When this heat energy is absorbed in the atmosphere, some energy is prevented from returning to space. This energy reradiates to moderate the changes in temperature from solar warming to night-time cooling.


II. Scenario

A commercial vegetable farmer from California (our client) has come to our Science Lab to request our help.

The recent droughts in the Southwest have caused many crops to fail increasing the local need for fresh vegetables from outside regions. Our client sees this as a major opportunity to increase his sales by shipping his vegetables to sell in this drought area.

He sent one truckload of vegetables to Santa Fe, NM, but when it arrived, the vegetables had spoiled and could not be sold. The trip is over 1,000 miles and takes 14 hours traveling through the desert Southwest.

 

III. Challenge

Each design group of four students in our Science Lab must examine the conditions and generate a hypothesis to explain why they think the vegetables have spoiled.

Your groups will then design and conduct an experiment to explore if your ‘guess' is correct. This should include a model that is testable and data measurements to determine possible causes.

After analyzing the data, your groups will arrive at a conclusion for the cause of spoilage and then develop a proposed design solution to prevent the next shipment of vegetables from spoiling during transit. Models of the solution may be built to be tested for their effectiveness.


IV. Limitations and Rules

The design solutions must utilize common materials that are readily available. Solutions must utilize the scientific concepts addressed in this Unit of lessons and not create imaginary materials or processes. Solution must meet local laws and restrictions for trucks on Federal highways. Fabrication and assembly costs must not exceed the cost of a current semi-tractor trailer. The proposed solution must be buildable within a time frame to be used before the end of this growing season (3 months). The success of each solution will be determined by the other design groups and by our client based on a perceived performance of the solution.

 

 

Conclusion:

Now you understand the how heat energy is transfered and can differentiate between the three different mechanisms of Conduction, Convection, and Radiation.

You can also correctly identify examples of each type of heat transfer and understand how the Sun is the major source of heat energy on Earth transferred by Radiation through space and converted to other forms of heat when absorbed by different materials. You can apply these principles to new situations to solve problems that involve the transfer of heat energy. Congratulations!

Assessments:

You will be able to...

Strong

4 points

Good

3 points

Adequate

2 points

Inadequate

1 point

Weighting
Demonstrate an under-standing of
the 3 methods of heat transfer
with examples of each
A complete under-
standing of all 3
methods of heat
transfer is demon-
strated with
examples of all 3.
A basic understanding
of 2 methods of heat
transfer is demonstrated
with examples of both.
A weak understanding of 2 methods of heat
transfer is demonstrated
with incorrect examples.
A lack of understanding of any methods of heat
transfer is demonstrated
with no examples.
25%
Develop a testable hypothesis
using heat transfer to explain
the vegetable spoilage.
Hypothesis
strongly relates
to heat transfer
and is
measurable
Hypothesis relates to heat transfer and is measurable Hypothesis is not strongly related to heat transfer and is not
measurable
Hypothesis does not relate to heat transfer and cannot be measured. 15%
Identify the forms of heat transfer
that may effect the
vegetable transport.
Correctly identifies all of the forms of heat transfer that may cause spoilage. Identifies some of the forms of heat transfer that may cause spoilage. Identifies one form of heat transfer that may cause spoilage. Does not identify a heat transfer that may cause spoilage. 20%
Develop a testable model to measure effect of heat transfer. Model successfully passes temperature and time performance criteria to prevent spoilage Model marginally passes temperature and time performance criteria to prevent spoilage. Model passes temperature, but fails time performance criteria to prevent spoilage. Model fails to meet both temperature and time performance criteria allowing spoilage. 20%
Collect temperature measurements
of heat gain on model over time and interpret
this data.
Temperature measurements of heat gain on model collected over time and data is reasonably interpreted. Temperature measurements of heat gain on model collected over time and data is weakly interpreted. Temperature measurements of heat gain on model collected over time but no interpretation of data provided. No temperature measurements recorded and no interpretation of data provided. 20%

Resources:

http://www.ucar.edu/learn/1_1_2_5t.htm
http://www.wisc-online.com/Objects/ViewObject.aspx?ID=sce304
http://www.youtube.com/watch?v=jXa-y6IzOYw

Teacher Notes:

Notes for the first demonstration:

Use the following text with the class. Answers are in parens.

I have a balloon filled with air and I have a lit candle. What do you ‘predict' will happen when I place this balloon in the flame of the candle? Write your prediction and write an explanation for what you think will happen. OK, let's see. (Flame causes balloon to burst). Now, write down what you observed and whether this is what you predicted. Write an explanation for what you observed.

Next, I have a balloon filled with water and the lit candle. What do you ‘predict' will happen when I place this balloon in the flame of the candle? Write your prediction and write an explanation for what you think will happen. OK, let's see. (Flame burns, but does not cause the balloon to burst). Now, write down what you observed and whether this is what you predicted. Write an explanation for what you observed.

What was your observation in the first trial? … In the second?

Can we all agree that the candle caused the balloon to burst in the first, but failed to burst the balloon in the second? Why? How can we explain this difference?

Let's explore how energy from light (radiation) effects the heating of different materials.

 

Image Credits:

Heat of fire, 4 September 2010, Sarah Reid, Flickr, via Wikimedia Commons

Soil, 27 September 2010, Mesaytsegaye, from Wikimedia Commons

Sunlight on water, 20 September 2012, by Gracemo,from Wikimedia Commons

Vegetable Truck, Photographed at the 2010 Autotron Classic car meeting, Rosmalen, The Netherlands. OLYMPUS DIGITAL CAMERA, 21 August 2010, by AlfvanBeem, from Wikimedia Commons

Kalabrien Ricadi Sandwellen 2129

Lamp grey

BurningFire.JPG

 

Additional diagrams from Wikimedia Commons