Did you know you can create a compound microscope and a refractor telescope using the same materials? It’s all in how you use them to bend the light. These two experiments cover the fundamental basics of how two double-convex lenses can be used to make objects appear larger when right up close or farther away.
Things like lenses and mirrors can bend and bounce light to make interesting things, like compound microscopes and reflector telescopes. 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.
Materials
- A window
- Dollar bill
- Penny
- Two hand-held magnifying lenses
- Ruler
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Download Student Worksheet & Exercises
- Place a penny on the table.
- Hold one magnifier above the penny and look through it.
- Bring the second magnifying lens above the first so now you’re looking through both. Move the second lens closer and/or further from the penny until the penny comes into sharp focus. You’ve just made a compound microscope.
- Who’s inside the building on an older penny?
- Try finding the spider/owl on the dollar bill. (Hint: It’s in a corner next to the “1”.)
- Keeping the distance between the magnifiers about the same, slowly lift up the magnifiers until you’re now looking through both to a window.
- Adjust the distance until your image comes into sharp (and upside-down) focus. You’ve just made a refractor telescope, just like Galileo used 400 years ago.
- Find eight different items to look at through your magnifiers. Make four of them up-close so you use the magnifiers as a microscope, and four of them far-away objects so you use the magnifiers like a telescope. Complete the data table.
What’s Going On?
What I like best about this activity is how easily we can break down the basic ideas of something that seems much more complex and intimidating, like a telescope or microscope, in a way that kids really understand.
When a beam of light hits a different substance (like a window pane or a lens), the speed at which the light travels changes. (Sound waves do this, too!) In some cases, this change turns into a change in the direction of the beam.
For example, if you stick a pencil is a glass of water and look through the side of the glass, you’ll notice that the pencil appears shifted. The speed of light is slower in the water (140,000 miles per second) than in the air (186,282 miles per second). This is called optical density, and the result is bent light beams and broken pencils.
You’ll notice that the pencil doesn’t always appear broken. Depending on where your eyeballs are, you can see an intact or broken pencil. When light enters a new substance (like going from air to water) perpendicular to the surface (looking straight on), refractions do not occur.
However, if you look at the glass at an angle, then depending on your sight angle, you’ll see a different amount of shift in the pencil. Where do you need to look to see the greatest shift in the two halves of the pencil?
Why does the pencil appear bent? Is it always bent? Does the temperature of the water affect how bent the pencil looks? What if you put two pencils in there?
Depending on if the light is going from a lighter to an optically denser material (or vice versa), it will bend different amounts. Glass is optically denser than water, which is denser than air.
Not only can you change the shape of objects by bending light (broken pencil or whole?), but you can also change the size. Magnifying lenses, telescopes, and microscopes use this idea to make objects appear different sizes.
Exercises
- Can light change speeds?
- Can you see ALL light with your eyes?
- Give three examples of a light source.
- What’s the difference between a microscope and a telescope?
- Why is the telescope image upside-down?
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I couldn’t find Washington – that’s were I live
Test
Since we’re still adding content to the grade level area, we don’t yet have a shopping list for it – so sorry about that! You can skim through and look at the experiments you want to do and quickly make a list for the ones you’d like to do.
Hi Where do I find materials list for 7th grade Life Science?
It makes the image appear smaller instead of larger. Try it!
Why can’t you use concave lenses for this experiment?
I’ll have my team contact you right away!
Hi Aurora, Why do I keep seeing sorry you don’t have access… when I paid for this grade level?
I apologize for the confusion! I am still adding bonus content to this section, so we don’t yet have the shopping list ready for download, so you’ll want to go through and find the experiments you want to do (not everyone completes all the experiments in tne sections, as there is a bit of overlap so you can pick and choose the experiments that fit your time and budget.) You’re going for quality, not quantity. 🙂
The list of experiments is on the main lesson page for the grade level you select. When you click on a post (experiment), the menu changes on the right to allow you to view more experiments in the related section in case you want to go deeper into the subject.
I’m planning on starting 7th grade life science with my son in a few weeks. Up to now I haven’t been using the grade level format, but rather the “topics”. As I’m browsing through the 7th grade life science section, I can’t find the list of items needed for the experiments in the unit (I found this easily in the other section organized by topics). I see links to lots of experiments but the grade level section doesn’t seem to be set up like the “topics” section. Where would I find the list of items I need to have in order to teach the 7th grade life science unit? Also, I clicked on the first experiment of the Life Science section titled “Simple Microscope and Telescope” and the links to the right of the experiment say “Astronomy introduction”, Astronomy Reading and Experiments. Don’t understand why these Astronomy links are showing up in the unit that is supposed to be about life science. Thanks for clarifying.
Thank you, I now have access.
I’ll have my team connect with you right away!
Why do I keep seeing sorry you don’t have access… when I paid for this grade level?
It may be a problem with your account. I’ll have Tonya get right back to you!
Aurora I don’t know where to do the next experiment if I can’t unlock it the only one I can do is this one because it says I’ve not unlocked the next thing what is the next experiment after this one that I can do.
Hmm… I am not sure of your question. Ask again a different way?
Answers to exercises are in a link on the exercise page, and in the downloads on the last page.
Hey where would my mom found the answers to the exercises/questions up top and above the comment bar.
After, because it’s got details and questions about the experiment. You can print it out ahead of time so you’ll have it when you need it. 🙂
Do they do the student worksheet first or after the video?