Activator+Strategy+(practica)

Type
ENGAGE - HOOK

Description
Kinesthetic Demonstration

A hook activator strategy is one that stirs students' curiosity and rallies their attention to the idea in play. I opened the hook by asking two simple questions that involved the hook's apparatus (a thick glass shelf measuring 5 x 26 inches and a nice glass marble, about an inch and a half in diameter). We discussed what would happen if I released the marble where I held it in the air (it would land on Nate's head) and what would happen if I released it on the surface of the //tilted// glass shelf (it would roll down). The class agreed that gravity would be responsible for these behaviors.

I chose 4 students randomly from among volunteers and assigned jobs of //Balancers// and //Chasers//. The //Balancers// we're tasked with holding the ends of the shelf and with bringing the marble to rest once I released it onto the shelf. The Chasers were there to catch and return the marble should that be necessary. Eventually I declared "pretty much success" and asked what was at work in that case. "Straight!" was a common keyword in students' responses. "Yes. Sure. Good!" I said. "But what does 'straight' mean?" I asked. I used this as an introduction to a short lecture that relied on diagrams from our gravity activity and introduced the idea of right angles, 90º, and the idea of //perpendicular//. Now, most students were well aware that right angles measure 90º and a few knew the word perpendicular, but I wanted students to build an understanding of these ideas by adding their intuition, observations, and analysis to newly learned concepts about angles. I wanted them to regard right angles as the //congruent, adjacent, supplementary angles// that are created when perpendicular lines intersect. I think that is a more vibrant understanding of the concept than just being able to remark that "right angles are 90º."

Middle school students (and others!) love hands-on activities and spectacle. There was immediate interest as soon as I held a marble in the air and talked about dropping it. Volunteering hands shot up before I had in any way revealed what activity the volunteers were vying for! There was evidence of considerable //audience// focus on the //performance//, and plenty of motor-break was afforded as everyone moved around to see what was happening. Though I could not measure it directly, I feel that seeing the consequences of a //tilted// shelf (a rolling marble) was a benefit for most students when I asked them to relate the idea of //straightness// to congruent and adjacent angles, and from there, that perpendicular lines make right angles (and a motionless marble).

I liked this activity and I believe it helped to create a rich learning experience. I was hesitant about doing it because I wasn't sure I could justify the time it required. Was it necessary? Would my students be able to meet Common Core standards without having this experience? Having these doubts in the back of my mind, I rushed through the experiment, trying to make sure we'd have enough time to practice more kinds of angle classification. If I teach this again, I will spend MORE time with it, not less, being sure that every student has a good view of the demonstration and holding out for better than "pretty much not moving." I think stopping the experiment too soon only works against the very reason for doing it in the first place. The right angles that the force of gravity makes with the shelf //should// be a hard-won, dramatic achievement. And arousing mathematical enthusiasm and curiosity //while// meeting CC standards //is// my job.