Day 61 – Direct Measurement Videos

Physics 11 – In preparation for the paradigm lab for unbalanced forces, today’s physics classes used Direct Measurement Videos (DMV) to analyze constant acceleration motion of a toy car.

The DMV we used were from Peter Bohacek at Carleton.  They are, simply put, brilliant.  Peter started making these videos a few years ago and in their most basic form, DMV are quite simple.  You shoot some video of an object moving and make sure there is some type of ruler in the scene.  Better videos will be shot at higher frame rates with better lighting, better apparatus and setups with very little lens distortion or perspective.  Once you have a video, you can analyze time (counting frames) and position.

Peter’s newest videos are put into an html5 video player with many more features.  For today’s class the DMV player we used allowed the user to pick different toy cars to analyze.

It took the whole class for students to get used to the software and gather data for analysis.  They were asked to find the acceleration of the toy car, but lots of students started collecting massive amounts of data and plotted position vs time graphs.  This was after we had a class discussion on how acceleration can be calculated directly from d = vot + 1/2at^2, or a = dv/dt, once you find the beginning and final velocity.  I’m not sure I’ll ever quite understand how students get off track so often (well, I think I know why, I just don’t know if I’ll ever get good enough to mostly eliminate it).

Day 60 – DNA Extraction

Science 9 – Today’s lab was to extract DNA from strawberries.  What a wonderful activity to do.  It’s easily accomplished with minimal expenditures, and while the students would not be able to devise the procedure themselves, the steps are somewhat understandable.  Smash the strawberries to break cell walls and membrane.  Soap further breaks down the cells and releases the DNA from the nucleus.  Ethanol makes the DNA percipitate out of the solution.  Heck, I wouldn’t even come up with the procedure.

There were lots of smiles going around the classroom today and there was a good amount of learning. It was good day at school.

Day 59 – Stories in Science

Science 8 – Continuing from Contagion, I thought I’d try something different in science class.  The idea is that encyclopedias are boring and that humans naturally communicate through stories.  RadioLab is a perfect example of this.  Together in class we listened to a story about penicillin and antibiotics. It was interesting, captivating, easily understood and memorable.

So why re-hash an encyclopedia when it would be better to gather information and then disseminate it through story?  Kids were given two options.  Turn their research into a short story, or make a presentation.  The presentation should also be a story of some kind.

There’s lots to write about this, but it deserves its own post. To make a long story short, I’m trying to collaborate with colleagues in the English department to work together on a science and story project.  Perhaps through some Pro D we will be able to pull this off next year.

Day 58 – Mini Review

Physics 11 – We’ve covered a bunch of little topics to date in forces: Fg, Fs, FBD.  I felt that today was time for some more practice, and I could tell from student questions while they were working away that this was a good time to go over some problems.  We also did a quick activity with masses and spring gauges to emphasize the difference between mass and force of gravity.