Day 10

I got off a few days somewhere along the line, but we’re good now. We just lost a few days to the dark ages. I also want to start posting a few pictures of student work from now on to supplement my visual learners.


I was really excited about today’s lesson now that we finally made it through the muck that is the undefined terms and midpoint formula (it’s really hard to make this stuff and awesome) and now we’re onto angles and lines. Most of my students are familiar with the basic information about angles–180 degrees in a straight line, 360 degrees in a circle, acute, obtuse, reflex, yadda, yadda, yadda. So I wanted to have them work on a task that required the students to use this information, but without telling them that. So I pulled out an old physics lab that I have never got a chance to actually use in physics class.

hinged mirror

The activity goes like this, you take two plane mirrors and ‘hinge’ them together with tape so that you can adjust the angle between the two mirrors, as seen in the image. Place an object in the middle of them and then count the number of reflections you see. I ask them to fill out a little table to help them organize the data and then to try to find the pattern that was emerging.

Of course not everyone has two plane mirrors for each student to perform this investigation so I got the next best thing, old CDs. The CDs work just as good as mirrors except for the hole in the middle which sometimes blocks out some of the image. Another helpful suggestion is to glue each to a piece of cardboard, so that the mirrors stand on their own.

The activity launches good discussions between students and ultimately provides a great platform to launch into the discussion of angles, circles, straight lines, etc. Another quick note, have a couple of mirrors already set up and demonstrate the procedure for your students. I made the mistake the first time of just verbally issuing instructions and when I got done no one had a clue.

After they finished the activity and we had a short discussion formalizing our findings and some definitions, I gave the groups an assignment that I got from Work Done concerning parallel lines that beautifully introduces vertical and interior angles.


In physics we broke out the spaghetti again. Since we are still working on the scientific method–specifically using data to make predictions and linear regression–I wanted to give students another hands-on activity as opposed to working on another worksheet. So I showed them my setup of a spaghetti noodle precariously positioned between two supports with a plastic cup hanging from the middle of the noodle by a string (a nod to the modeling curriculum). I then asked them what are some things we could measure if we started adding small masses to the cup. After a couple of off-the-wall ideas were thrown in, we settled on how much mass would it take to break the noodle–and off they went.

The groups started precariously adding masses to the cup. Crashes resounded throughout the room during the first half hour of class, each time followed by students quickly getting up to scribble numbers into their lab notebooks before repeating the whole process again. After all of the data were taken I had a list of questions for students to answer regarding their data, primarily asking them to make predictions from their equation.

  • How much mass could 10 noodles hold? 20 noodles? 50 noodles?
  • How many noodles would be necessary to hold 5 kg?
  • What are the units of the slope of the line?

Some of the students felt very confident with the math necessary to do this–it is the fourth time we have done it in class–but a few were still lost and were even more upset to find out about the upcoming quiz. I was very impressed with the fact that the students who had figured out the process were quick to get up and help out their neighbors, I love that collaboration and have been doing my best to foster a student-first class.

I was also surprised to see the level of interest from the students in the task. It is amazing to me that students find some experiments totally cool and others, just, not. Even though they might be very similar to each other.


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