1. Start this activity by projecting (via computer presentation or color overhead transparency) the visible light and infrared light images of Old Faithful. Image Set 1 of the Image Appendix contains a variety of visible, infrared, and combined (side by side) views of Old Faithful for you to choose from.

Image Appendix, Image Set 1: Geysers (Section VI, A): (MS word version | pdf version)

Note that these images have had the temperature legend stripped. Additionally, refrain from referring to them as "visible light" and "infrared light" views as it may give too much away at the beginning of the activity.

2. After reviewing your choice of the images, project one of the side by side (visible light and infrared light) images from Image Set 1 of the Image Appendix (Section VI, A).

3. Ask a few probing questions to get their curiosity flowing.

Sample Probing Questions:

• What is this picture (visible light) of? [a geyser]
  
• What do we know about geysers? [they shoot hot water into the air]
  
• What is *this* picture of (infrared light)? [looks like the same geyser, but is different colors/not what our eyes see]

4. Encourage your learners to express their curiosities about the infrared view of the geyser. Example: What do you want to know about this (infrared) image?

Suggested Key Curiosities to encourage:

• What do the different colors represent?
  
• How was the picture taken?

5. Once keyed into the suggested curiosities from above, dive into a brainstorm class discussion that will cover the following points:

• The normal (visible light) picture is of a geyser that shoots hot water upward from underground.
  
• The "new" picture (infrared light) is unknown, but seems to be taken at the same time as the visible picture.
  
• The "new" picture (infrared light) seems to be color-coded and we think that the different colors represent different temperatures.
  
• The "new" picture (infrared light) is maybe a recording of non-visible wavelengths of light: radio waves, microwaves, infrared light, ultraviolet light, x-rays, or gamma rays.

6. Once the last two points above are expressed by your learners, you are ready to move forward into an activity focusing on infrared imaging.

B. Exploring Infrared Imaging

Activity Time: 25-45 minutes

This lesson is a mini-exploration and serves as an introduction to infrared imaging. At the conclusion of this exploration, your learners should understand the following: Infrared cameras can detect how much infrared radiation/light an object is emitting

• Infrared images (like the ones here) show how much infrared light was detected by the camera. Infrared light is used to measure the heat emitted by these objects. This measurement is transferred to color codes and is equivalent to degrees Fahrenheit.
  
• The infrared image has been scaled to show the temperature of the various areas of the object using a false-color map.
  
• False-color maps, like the infrared images here, come with a legend that tells the observer which temperatures are associated with which colors. This is how someone can accurately interpret the image.
  
• By looking at or observing the images, one can determine warmer or cooler areas. One is unable to do this with visible light images.

This activity is common to many of our lesson guides. Please go back to Exploring Infrared Imaging to access the lesson guide.