Wednesday, August 1, 2012

Do We Need Light To See? Part 1

The video workshop Private Universe features a segment on student misconceptions about sight and light.  So I decided to give it a try since my state content standards focus on these concepts.  Here's the approach I took.

In the past, I tried starting lessons with KWL.  But frankly, I saw this as a waste of time.  I decided I had content to share with them so let's get to it.  I figured my students had various amounts of knowledge and questions about the topic.  It didn't matter because I was going to present the content and fill in any gaps they had.

But now I have a different intention for this pre-unit questioning.  It is to discover misconceptions students may have.  So I started this unit by doing a concept map.  I started with the question how does the eye work?  I wrote whatever students told me they thought they knew, even if it was a misconception.  That way, as we progress in the unit, students will be able to revise the concept map and see their learning.

Then I asked students to write down questions they have about how the eye works.  I went through the questions and found many students have the same questions:  Why do we see upside down?  Why does the pupil get bigger in low light and smaller in bright light?  Why do we have different color eyes?  We talked about what makes a question testable or researchable.  We decided (with my prompting) that the first two were testable.  One of the things I realized from these questions is that students do not realize the pupil is a hole which lets light into the eye.

One thing I noticed from the concept map is hardly anyone mentioned that light is needed to see.  I probably would not have noticed that if I hadn't watched Private Universe.  I decided this was the concept that I would target for their learning.

I challenged them by asking them if they thought they could see in the dark.  Initially, some said no and many said yes.  As I questioned further, I found that some that said no revised their response when I questioned them further.  I asked if you are in a completely dark room could you see shadows, shapes, or movement.  Many of the students who initially said no said you, you can see shadows, shapes, and movement.  They also said they'd be able to see these things after their eyes adjusted.

I asked them to write down what they thought they'd see in a completely dark room with no light.  Then I asked them to draw a diagram showing how the eye sees a red apple.  Many were at a loss.  So I prompted them to draw an eye and an apple and to draw arrows showing me how the eye sees.

Just to let you know, at the beginning of the year, we had talked about how we see color.  That some light is absorbed by an object and other light is reflected into their eye which our brain reads as the object's color.  When I saw their drawings, I realized most had not learned this concept.  I was blown away!  Most of the students drew an arrow coming out of the eye.  I questioned them.  They suggested that sight comes out of the eye!  This was the majority of my students.  Including my two honors classes.  And hardly any students drew a light source.

In a future blog post, I will share the activities that I used to challenge these student misconceptions.

No comments:

Post a Comment