Defining Force

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Students will be able to define force qualitatively and as a vector quantity, while also identifying the different types of forces.

Big Idea

Students find out just how much they really know about forces.

Show What You Know

10 minutes

Today's class starts off with students showing what they know. I have the word "force" written on the front board and have students pick up a blank piece of paper as they enter the room. Once the bell has rung, I ask students to write down anything and everything they know about force. They should be working on this individually, as I'm using it as way to assess any prior knowledge. This teaching strategy is also meant to help the students shift their thinking from 2-dimensional motion into forces, Newton's First Law, and equilibrium.

Once a full 5 minutes has passed, I choose a student to share an idea from his paper. I usually pick the student closest to me, and after he's shared I write his idea down on that front board. We then go around the room and students continue to share, but once a contribution has been recorded it cannot be repeated. This process continues until all ideas have been shared. I leave our example on the board in the hopes that we'll refer back to it throughout today's class.

While students are sharing their ideas, I am internalizing the information they are contributing. Looking at how much, or how little, they know helps me to adjust my pacing and depth for today's class and the entire unit. I'm also trying to identify any misconceptions that were shared so that I can be sure to address and correct those throughout the unit.

Defining Force Exploration Activity

30 minutes

Because I know from our introductory activity that my students have a working knowledge of force, students choose a partner and take a computer from the cart at the front of the room. As the computers are booting and after students have seated themselves next to their partner, I direct students to go to my website and download force exploration. This document is a guideline that helps students identify the absolute minimum material they should record into their physics notebooks. Once they've opened the document, the students follow the link to the Force Section of the Physics Classroom. At this website and still in their pairs, students read through the text and use the document to guide them through the process of defining forces (both as a vector and the different types of forces that exist). I let students know that they can read aloud or individually, but the point of them being in pairs is to discuss and determine the most important parts of the text.  

While students are working, I walk around with the answer key to ensure they are actively engaged in the learning process. To me, this means that they are on the proper website, reading or discussing some component of force, and writing down a thorough set of notes. When I walk around, I spot check their written work and engage students in questions such as "Mathematically, do you have any ideas how we could prove force is a vector?" or "Have you heard of any of the individual forces before?" I also use this time to build rapport with students and attempt to make the material meaningful to the individual. For example, if I know a student is preparing to get her driver's license soon, I might ask her "Which forces from that list will be acting on your car while you're driving down the highway?"  

Closure with Hand Signals

5 minutes

My students often work through the force exploration activity at different paces, so the end of class today will not have a group closure session.  Instead, as each group comes forward to return their computer to the cart I ask each individual "How do you feel about the definition of force?  Could you take a pop quiz on it tomorrow if I gave you one?"  Students respond to me with either a thumbs up, thumbs down, or flat hand.  A student who shows a thumbs up would feel confident in his or her ability to succeed on a pop quiz over force, while a student showing a thumbs down would feel the opposite.  A flat hand indicates that the student feels indifferent about forces and the possibility of a pop quiz during the next class hour.

My students gave me a majority of thumbs up, so I plan to follow through and give this pop quiz tomorrow.  The hand signals give me a nice informal assessment of each individual, but I also want to formally assess that each student internalized the concepts of force.  If the students had given me mostly flat hands or thumbs down, I would have adjusted my unit plans and added another day to cover the definition of forces.