One thing I think I am going to try to do a better job with is in sharing my teaching material on this blog. Already, all of my lessons are digitized (you wouldn't expect anything less, would you?) except for the few extremely brilliant things I found in resource books, such as the 3-d spatial puzzles that I had spun into a multi-day computer project.
I have to be careful though, because ultimately this is not a teaching blog. I mention a good amount of teaching in here, because -- well, I am a teacher and I love my job. But for me, my experience as a teacher is intrinsically tied (for now, anyway) with my experience living abroad. So, for now, I have no plans of forking off a separate blog for just teaching materials. But, what it means is that, when I do discuss teaching, I'll try to be more thorough and to provide digital examples of my work. And I'll file all of those entries under the tag math stuff, for easier retrieval. (In fact, if you go back and look at the older entries, you will notice that I have already updated them to contain some screenshots of my older work! I am committed to this...) It is indeed possible that in the future, I would want to create a comprehensive digital portfolio of the blogs I read, the bookmarks I keep, the blog entries that I write, along with my favorite digitized lessons. But, I don't see that happening before we settle back in the States, because I'm already having a hard time keeping up with the maintenance of one blog, let alone two!
Anyway, a running list of ideas for teaching about circles (some of these might be too difficult for 9th-graders, but I thought I'd jot them down anyway):
- Take a motion-blurred picture of a fan, and using the shutter speed (and the picture) to figure out how many times the fan blades revolve in a minute while on different settings. Inspired by Dan's post about tennis ball dropping freeze-frame lesson.
- Discuss how we can measure the amount of material it takes to build a basketball and baseball, and using the discussion to highlight the difference between surface area (rubber of basketball) and volume (filling inside baseball) of a sphere. Courtesy of Ms. Cookie!
- If you stand at different latitudes on the surface of the Earth, how fast are you traveling at each location, as the Earth rotates about itself? (Alternately, if the ozone layer hole stays relatively constant in its location relative to Australia, then how fast must the ozone layer be traveling near that part of the world?)
- Taking a picture of a circular lawn and developing a lesson around how much fertilizer you would need, how long it takes for you to walk around the lawn, how long for you to mow the lawn, etc. Dan's post for how to do this correctly.
- If you slide a beverage glass on the floor, it always comes back to where it started after making a circle. Why? Which glasses make a bigger circle (and how much bigger)? Another of Dan's popular posts.*
- Circular probability - dartboard, Wheel of Fortune, etc. (This is very project-worthy.)
- Wheels, distance traveled/pedaled, and gear ratio. How do bikes work?
- Clock hands - how far (in degrees or distance) do they travel in a given amount of hours + minutes?
- Intensity of radiation as a function of distance from source.
- Circular mirrors (ie. Christmas ornaments) and their tangent lines. Where do you have to stand in order to see your friend reflected in the Christmas ornament?
Am I leaving out any good ones that are immediately obvious? The exciting thing is that I can teach basically everything related to circles using these examples. The obvious drawback (as always) is that it would take a long time to get through all of these activities, for just one unit! Sometimes I wish we had unlimited amounts of time.
*By the way, you might have noticed that I really like this guy Dan. He's awesome! He has re-inspired me to look at how I am teaching every topic more critically. Don't over-scaffold and think you're helping the kids; guide their thinking so that they can figure out what questions to ask and what type of data to collect! Love. It.