Eye Get It! Cow Eyes, Telescopes, and Convex Lenses

By Stacey Burt on October 7, 2011
  • Grades: 6–8

One of the most complicated ideas I teach is the difference between concave and convex lenses and how they are used in telescopes. Over the years I have tried numerous different resources and websites to assist me with instruction in this area. About five years ago during a cow eye dissection, as part of a study on the human body and body systems, one of my students turned to me and said, “Wow! Look at the way the lens magnifies the print on this paper! It works like a convex lens!” That was my “aha!” moment.


We know that it is always best practice to integrate different content areas when teaching, so why combining this lab with the study of telescopes and lenses had never occurred to me, I had no idea.  If you are experiencing the same frustration with the teaching of concave and convex lenses, here are resources you might use to complete a cow eye dissection in your classroom.

One of the best strategies EVER for conducting a cow eye dissection in the classroom is to check out first-hand how it is done. While there are several books out there, my favorite is Cow Eyes, Beef Hearts, and Worms by The Wild Goose Company. It is a great resource to have for basic dissections. However, the best go-to resource for a true, visual experience of a cow eye dissection can be found at the wonderrful Exploratorium website.

It goes into great detail describing how lenses work and provides a video of a cow eye dissection for you to view before you conduct your own lab. It could also be used as an alternative for the dissection itself if time, money, or a weak stomach is an issue. As for where to purchase your cow eyes, I suggest Carolina Biological. It is the resource that I have had the best luck with as far as reliability and quality.

I know this will be a lab and a learning experience that your students will never forget! Making concave lenses a hands on experience has never been so much fun and connecting it to telescopes and other uses should be simple after this experience.




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