To understand how telescopes work and how they can contribute to our knowledge of the universe.
Technology provides the eyes and ears of science. At this level, students can now begin to develop a broader view of technology and how it is both like and unlike science. Students tend to see both science and technology as tools to make things happen. They should increasingly be made aware of the distinctions between trying to learn how something works and trying to make something happen.
Students should also begin developing an understanding of the relationship between science and technology. Technology can provide the motivation and direction for scientific research as well as the tools to carry it out. New technology often requires new understanding; new investigations often require new technology. (Benchmarks for Science Literacy, p. 46.)
At this level, students should also become more aware that telescopes magnify the appearance of some distant objects in the sky, including the moon and the planets. The number of stars that can be seen through telescopes is dramatically greater than can be seen by the unaided eye. (Benchmarks for Science Literacy, p. 63.)
In this lesson, students will learn how telescopes work, will build a model of their own, and will consider how real telescopes can be used to ask—and help answer—questions about the universe. This activity is based on instructions and information from the Exploratorium website.
Begin this lesson by asking students what they know about telescopes. Most students should know that these optical instruments are used to view distant objects. You might want to point out the meaning of the word parts tele ("distance") and scopos ("to watch") and elicit other related words (e.g., telephone, television, gyroscope, kaleidoscope, microscope).
Continue the discussion by having students consider the following questions:
- Why can't you see objects that are very far away with your naked eyes?
- How do telescopes make distant objects seem closer?
Allow students to discuss their answers to these questions. Help them understand that the reason we can't see distant objects is that our eyes are too small to collect enough light from the objects. A telescope is like a huge eye that can gather more light from an object and magnify its image so we can see it clearly.
Tell students they will now have the opportunity to learn more about how telescopes work and to build their own model telescopes.
Prepare students for the activity by giving them some basic information about telescopes. A good source for your information is How Telescopes Work on the How Stuff Works website.
Then have students access the Looking into Space student esheet. As outlined in Steps 1 and 2 of the esheet, have students go to Make Your Own Telescope. Then direct their attention to the "To Do and Notice" section and make sure they understand the illustration.
Then, as noted in Step 3 of the esheet, distribute the materials and have students work in pairs or small groups to construct their model telescopes, following the instructions on the website.
Explain that, although their model telescopes can't be used to examine the sky, they do show students how real telescopes work.
Point out that there are two basic types of telescopes—refracting and reflecting—but that both work by collecting and focusing light and enlarging an image. Explain that, in this lesson, students will learn about and make a model of a refracting telescope. Make sure that students understand the terms objective lens and eyepiece lens and discuss the diagram of a refracting telescope included on the website.
Ask students to think of questions they have about the universe and how telescopes might be used to answer them.
Have students take the Tele-Challenge as outlined in the Understanding What You Learned section of the Looking into Space student esheet.
To prepare for this, post the following "tele-questions" on the wall or chalkboard about 15 or 20 feet away, and have students move their telescopes to one side of the classroom.
- How do the two lenses of a refracting telescope work?
- In your model telescope, what does the flashlight represent?
- What kinds of information can telescopes provide about the universe?
- In what way can a telescope be considered to be a time machine? (Hint: Think about how far away the objects in the sky are.)
- How could you make your model telescope more effective or powerful?
- How might scientists use what they learn about the universe to help them build better and stronger telescopes and other instruments?
Have students read the questions through their telescopes and discuss the answers with their partner or group. Allow each pair or group to present its answers to the class. A Take the Tele-Challenge teacher sheet with the answers to these questions has been provided for you.
Encourage students to continue exploring what telescopes can teach them about the universe by experimenting with a real telescope, visiting a planetarium, and doing research.
This lesson may be supplemented by the following related Science NetLinks lessons:
- Exploring the Solar System helps students learn about the geology, composition, and orbits of other planets by planning a trip to another planet.
- The Sun presents our local star's structure and features such as sun spots, magnetic fields, and solar flares.
- More information about the properties of light energy from the sun can be found in Harnessing Solar Energy.
This lesson is part of a series of Science NetLinks lessons dealing with optical technology. The other lessons in the series include Magnify It! (K–2), Seeing Around Corners (3–5), and Watch Your Thoughts! Diagnostic Imaging and the Brain (9–12).
More information about refracting and reflecting telescopes, how they work, the most amazing of them all—the Hubble Space Telescope—and the universe it is revealing can be found at the following websites:
- The Student Telescope Network is sponsored by Delaware University and offers many links to information about telescopes and the universe as well as Internet access to a working telescope.
- Ask an Astronomer is a site sponsored by Cornell University that offers detailed information about the components of the universe as well as an interactive format that allows students to get answers to their own questions.
- The Hubble Project is the official site of the Hubble Space Telescope and includes information on its technology and projects and an image gallery complete with animations and live video.