Student slideshow: English | Spanish

Teacher printout: English & Spanish

Reading in the Dark

In this reading, adapted from an episode of the podcast "Science Update," students learn if reading in dim light can impact your eyesight.

Students test their vision in the classroom.

Why does a lens make an image appear upside-down?

The lenses in your eyes are known as “convex” lenses: they’re curved outward. As light rays enter the far edges of a convex lens, the light rays are bent inwards. In other words, light rays entering the top of the lens bend down toward the bottom of the retina, and light rays coming in from the bottom of the lens bend toward the top of the retina. This is why the image looks upside-down! You might wonder: Why don’t we see everything upside-down? That is a question which puzzled scientists.

Light makes an upside-down picture on the retina of your model eye. The picture on the retina of your real eye is also upside down. So why don’t you see everything upside-down? Ask your students if they can think of an experiment that might answer this question.

Here's an experiment some scientists tried. They had someone wear eyeglasses that flipped the picture in their eyes so it was right-side-up. To see what happened, watch this video.

It turns out that the answer is not in your eyes -- but in your brain. Your brain learns to make sense of the picture in your eyes -- whether it's right-side-up or upside-down.

You can elaborate student learning and engagement with Mystery Science mini-lessons.

• How do you know if you need glasses? In this mini-lesson students explore how the structures of our eyes affect how clearly we're able to see.

If you are in an NGSS state, this mini-lesson supports the DCI LS1.A: Structure and Function

• How is a rainbow made? In this mini-lesson students discover how light is responsible for creating rainbows.

If you are in an NGSS state, this mini-lesson supports the DCI PS4.B: Electromagnetic Radiation