Force Tables: Staying Organized in Physics

[Earlier this week, Tina asked me my blog’s name. Truth is, I never named it. Sure, I bought a domain but I never got around to branding the blog with the same name. So, what’s up with the domain name? Kalamity Kat was my grandfather’s WWII aircraft, a PBY-5A Catalina flying boat. He and his crew were shot down while rescuing downed fighter pilots out of Tokyo Bay.]

Physics class. The topic is forces and my kids were struggling to solve problems like this:

A student of mass 63.1 kg decides to test Newton’s laws of motion by standing on a bathroom scale placed on the floor of an elevator. Assume that the scale reads in newtons. Determine the scale reading when the elevator is accelerating upward at 0.7 m/s2.

or this:

A basketball with a mass of 0.4 kg is being pushed across a gym floor with a horizontal force of 2.2 Newtons. The coefficient of kinetic friction between the basketball and the floor is 0.2. What is the acceleration of the ball?

Struggling, that is, until I hit upon a way to organize their thinking with a “force table”.

this is what I've been calling a force table // yeah, I realize there's lab equipment with the same name

Students fill in the table like it’s a Sudoku puzzle. I think the hardest part now is getting the free body diagram correct. Ooh, just to be sure they know what’s up, I’ve been stressing the importance of completing the last column with justifications.

I like to imagine that all the physics teachers out there trained in physics education went to grad school classes with titles like “How to Teach Kinematics” and “Methods for Helping Kids Who Suck at Math”. In these imaginary courses, y’all received the keys to helping kids past the hurdles of difficult math or “there’s no formula for this, it’s a problem-solving process”. Wait. What? You didn’t have these classes? Then how the heck do you help kids problem-solve? Please share your own organization routines, I’d like to learn from you.

3 thoughts on “Force Tables: Staying Organized in Physics

  1. Pingback: Force Tables: Staying Organized in Physics | Productive Struggle

  2. Thanks for the clarification on the domain. I linked back to this post from the Productive Struggle blog because the question you’re asking here is big, important and I personally want to know the answer!

  3. With word problems (aren’t they all?), I have kids *box* any information they can recognize (number & unit, “at rest,” “comes to a stop”). Often kids don’t recognize that numerical information is given in verbal form. What they are looking for is *circled.* Yes, kids comment/complain that this seems like English class sometimes.

    As for the tables, I do something similar whenever I can. In kinematics the rows are x/v/t/a and the columns are initial/final values with questions. I have them circle the square to indicate what they are looking for. If a 2-step problem, kids can initial/middle/final the columns. Also, have them sketch a semi-qualitative position-time and/or velocity-time graph (marking the major info – t sub zero, t final, v sub zero, etc).

    A few years ago, my kids came up with something similar while doing energy pie charts (they markedly preferred this over the circles). Rows are energy storage (Ek, Eg, Eel, etc); columns are each snapshot/instance. Where I came in: in each square is:

    check = NRG account that is present
    arrow up = increase from previous snapshot,
    arrow down = decrease from previous snapshot
    dash = no change

    If there is no energy in that account, put a zero. The first time it is used, that’s a check mark, then arrow up/down for increasing/decreasing. The same sort of thing goes for gas laws (P/V/T/n = rows, initial, final, arrow up/down or dash = no change). Th

    I found it helps to have these tables on quizzes/tests ready to be completed as part of the question. Some may disagree, but I found (especially for weaker students), they would do better if they knew that these tables were part of the assessed/graded problem – and not get so lost.

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