Curse your sudden but inevitable betrayal!

So, on Friday I passed out the Algebra 2 CPM books I convinced my school to buy.  And today, the very first lesson out of the book… I’m disappointed.

Ok, not REALLY disappointed.  The book has us doing some basic practice problems for a day, finding parabolic sections that go up 4 feet and are 8 feet wide, or that go down 15 feet and are 40 feet wide, etc.  The problems are structured in such a way that students will discover a method for algebraically determining a in y=a(x-h)^2+k, which is great.  It also brings back the idea of domain and range, and asks the kids to define their own, which I think is fantastic (another post: domain and range should be used more often in a more sensible way).  So, as boring practice problems go, these one at least have some inherent self-discovery lurking.

But every single problem is boring, and worse, every single problem suffers from the classic burden of pre-printed, static materials: they must explicitly identify all of the information needed to solve the problem, and they don’t give any extraneous information.  The students need not think about anything outside of the printed page.

So, I’m replacing this, the very first lesson after my free-time-enabling, curriculum-guiding, all-but-cocktail-mixing miracle books arrived, with one of my own.  I based it on Dan Meyer’s WCYDWT: Projectile Motion photo, but made a couple of improvements:

  1. I reworked the geogebra file so that the photograph could be moved by the students.  More importantly, the photograph zooms correctly when students zoom in and out.  I did this by:
    1. Creating a point, called A.
    2. Creating a line with the equation y = y(A), giving us a horizontal line that will follow A around.
    3. Creating a point called B on the line from the last step.
    4. Inserting the photo, then using its properties to specify that A be one of its corners, and B another.  Now, students can resize the photo and move it anywhere they like, but cannot rotate it.  I made the line invisible, and made it an auxiliary object so that it would not appear in the object list.
  2. After looking at the photo (briefly) as a whole class, I split the students into groups of four, and gave them this worksheet (docx).Small groups are the freaking way to go, man.  Even in my small Algebra class (only 12 students!) if I have a full-class discussion, 5 or 6 kids aren’t going to say anything.  In groups of 4, maybe I have one kid per day not speaking and sharing.  I imagine the difference in participation percentages would be exaggerated in classes of 30.

So, CPM is totally great, but some of my commenteers were right: it is not mixing my drinks for me.  I think my lesson was an improvement over CPM’s – but it’s important to remember that, though I changed details of this lesson, I am still operating in a research-proven structure and curriculum.  I don’t need to worry that this lesson would have been better delivered in a month, or three months ago.

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