By Eric Brunsell
Posted on 2010-12-27
From January’s Science 2.0 column: Picture This Assessment
“I have often used microscopic images of everyday objects as warm-up exercises to start class, and to get kids involved in making observations and asking questions,” says John Burk, a ninth-grade physics teacher at Westminster Schools in Atlanta, Georgia.
Check out this example from Burk’s class blog (Note: He uses this cheap microscope and a camera to get the pictures):
Ok, so we’re rocking through these. Here’s one more. Remember, questions are more important than answers. But I do have one for you. How many yellow jacket antennae hairs would fit in this?
ps. If anyone wants to share their own “What is this photos”, feel free.
And here are some of the student responses:
Student: A crack in the sidewalk maybe?
Student: Its 20 micrometers, or 20 millionths of a micrometer. It could be part of skin, like a fingerprint.
Student: Yeah, I agree with Wendy. It might be a trench or a ditch in the ground.
Burk: Look closely at the image. How big is this crack or ditch?
Burk: How big is it? How big is a normal sidewalk crack?
Student: totally random but i think its pencil lead.
Burke: But how do you know? Questions are more important than answers. How big is this thing?
Student: I think that it looks a bit like an indentation in clay. Like someone dragged their finger through it. So that would mean the actual crevice is about the size of a finger. The roundedness of the indentation makes me think that it is a clay or a softer materials. Any other soft materials that could have indentations like that?
Burke: This is progress! But look closely at the picture what does 20 um mean? (The symbol is actually the greek letter mu) Is that equal to 1cm (which is your finger)? And why would you be making indentations, anyway?
For more of the discussion…and the answer, go here.
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