Through Their Eyes: First and Second Graders Consider Insect Vision and How Scientists Might Study It

Article excerpt

How do insects see? What do scientists really know about their eyesight? These kinds of questions are at the heart of inquiry, and teaching about the nature of science is critical to understanding why the knowledge science generates is so powerful. Insect vision is an area of active research that allows fruitful exploration into the nature of the scientific endeavor because of the bias our own vision brings. As scientists, we use our senses to make observations, but we can't assume that what we see is what insects see; we are forced to think outside of our own senses when we ask questions about insect vision.

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We considered these concepts as we guided a first--and second-grade integrated class in thinking about what scientists currently know about insect eyesight, the complex issues scientists face when trying to understand what insects see, and how students as scientists can begin to investigate eyesight.

Introducing Eyes

We began this investigation by inviting students to think about the way humans see. This is an essential part of the lesson because it is important for scientists to think about how their own perspectives may influence the type of evidence they can gather. We explained that our binocular vision relies on the fusion of the images our two eyes receive. To help students see how our brains compensate for this binocular vision, we gave each student a cardboard tube (e.g., a paper towel roll cut in half or a rolled-up piece of construction paper) and instructed them to cover one eye and hold the tube up to the other. Demonstrate how to safely hold the tube near the eye.

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Students were instructed to focus on an object on the wall and slowly move their hand away from their covered eye, stopping once they could see the object on the wall "through" their hand. We wanted them to think about what their brains were seeing versus what was really there.

We then tried a simple exercise to get into the head of a fly searching for food. Working in teams, one student was the "fly" and the other was the "cheese." The flies closed their eyes while the cheeses went to stand somewhere in the room. Flies were instructed to hold two tubes up to their eyes and look only through the tubes. Students pointed the tubes out to the sides of their heads like insect eyes, not straight forward like human eyes--the flies then had to find their partner, turning their head back and forth to navigate. Remind students that they should not race around to find the cheese, but to look for the cheese and then to think about what they could see and couldn't see by only looking through the tubes. Create an area free of trip hazards, and remind students to use caution as they move around.

Though this is a simplified version of how flies see (find out the accurate story on insect ommatidium in Science 101 on p. 70), the point of the exercise was to give a tangible experience processing visual cues in a way that was different from our life experiences.

After the students had tried to navigate in this manner, we used a series of open-ended questions to help them reflect on their experience with "fly eyes" and to compare it to how they see using their own eyes. Some example questions included: How hard was it to move around? Did you have to constantly look around? How long did you think it would it take to find real food? How hard was it to maneuver around obstacles in the room? What if there had been any predators around--would you have been able to see them? Our goal with this questioning approach was to encourage discussion and model how asking questions is a part of the scientific process.

Next, we explored how our brains process visual cues. Optical illusions provide excellent tools for examining how our binocular vision influences what we see because they make use of how our brains process the images our eyes receive. …