Day 61: Onion Root Tip Lab

slides

Science 9 – Today I thought I’d have the students try a microscope lab.  This is a pretty typical lab that is frequently done across all schools. Students are asked to examine a slide under a microscope and to see if they can recognize cells that are in the various stages of mitosis.  I think this lab would be extremely difficult with the above graphic to help.  At first, students will just see a few hundred cells that all look the same. It takes a reasonable amount of time before subtle differences are seen.  The above slide is more clear than what the students actually see because in order for the students to have this level of magnification the depth of field is much smaller.

One of the hardest things for the students to do is to actually get a slide in focus.  I had to spend a lot of time helping with this. My first suggestion was for them to initally focus on a piece of lettering that was on the prepared slide.  However, many students would only have their slide in partial focus. I found that very interesting – I don’t know why a person would stop focusing, or keep playing with the focus and see that the sample because sharper and sharper.

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