Unit 6: Back to the model...

I'm proud to say that I've actually gotten back to the concept of a "model" for Unit 6.  No PowerPoints, no lecturing.

On Friday, students observed prepared slides of an onion root tip:

Random image from Google Images

Students were asked to draw the different types of cells they see in their lab notebooks.  I then had them get together with their lab groups and white board a consensus of the different looking cells in the onion root tip:

I told them the squiggly lines were chromosomes and we confirmed as a class the only organelle we could clearly see was the nucleus.  After discussion, we came to a consensus that the cells were dividing to make new cells so the root could grow.  As a class, they put the images in order (as best they could based on the drawings) and I told them that each of the images was part of mitosis.  I then gave them the name of each phase.

We then created a class "model" for cell division:

Students then completed Exercise 1, where they verbally explained each of the phases and calculated the percentage of cells in each phase based on a picture of what they had seen in the lab.

All was well until I attempted the Popsicle Stick Chromosome activity.  For this activity, I spent WAY too long creating popsicle stick chromosomes from the images included in the curriculum.  The notes suggest affixing chromatids together with velcro... I had adhesive magnet strips on hand, which I thought would work and save me a trip to Walmart.  Nice idea in theory, but they all proceeded to fall off as soon as the students pulled the sticks out of the baggie.

Lots of effort on my part for very little gain...

I attempted this activity with two of my classes.  It was such a bust with each class, that I skipped it the rest of the day.  Students struggled with pairing the shapes.  Students struggled with the concept the shapes represented genes, despite watching an interactive video on chromosomes before.  The notes say to give the students a baggie with 4 chromosomes (2 pairs), and have them try to model mitosis.  They're supposed to come to the conclusion that they don't have enough chromosomes, so the chromosomes must duplicate.  My students weren't coming to that conclusion.  Then when I gave them additional chromosomes, they couldn't attach them as intended, so they really weren't understanding anything-- they just thought they had 8 chromosomes.

I'm not sure if I'll attempt this activity again, but I've already considered some ideas to improve it-- like actually using velcro like it says, for starters.  Also, numbering the baggies for easy handout and making sure all the baggies are identical would prevent chaos.  My baggies got mixed up a little between classes, which just exacerbated the disaster.

Students then completed Exercise 2 using the textbook for assistance, applying the information learned to revise our "model" with more detail about each of the phases of the cell.  Although I'm sorry to say, I feel like my students had a better grasp on mitosis and cell division on Friday, prior to the popsicle stick debacle, Exercise 2, and expanding their "model."

We're doing the Web Quest on chromosomes tomorrow-- which was ideally supposed to be done before Exercise 2.  I couldn't get computers until Wednesday.  Now I'm somewhat regretting my decision to even do the Web Quest... my students never seem like they retain anything from them...