Mo Physics Mo Problems

As a teacher I like to think of myself as someone who values the process of problem solving rather than the right answer.  But, when I look at the majority of problem sets I assign my students, they simply focus on an getting the right answer. The problems ask only about the end without highlighting the thinking that goes into it.

When I think about all the work we do in our literacy training of analyzing a prompt, that work goes out the window when I give a student a calculation. I am always frustrated when students simply write down an answer to a complex problem without showing the work that went into it. But, I've come to realize that's what my practice problems have trained them to do.

Basically, I've been asking the wrong questions this whole time.

So, I'm rewriting my problems to force students to think through the process and respond.

As a physics teacher, we have a number of formulas that students must choose from to solve a specific problem. What I've found is that students don't have issues plugging numbers into a formula.  The problem comes with figuring out the formula to use for the situation.  Ultimately, that is the understanding I want them to have. I want them to be able to look at a situation and understand which tool to apply to that situation in order to solve it.

For my practice problems, we use a learning management system which autocorrects.  So the majority of the work we do for practice problems is with multiple choice or numerical responses.  So, it is up to me to break down the problems to very intentional chunks to force students to go through the thought process that is often taken for granted.  I’m not looking for students to simply plug and chug. I want them to be able to analyze the information given and choose the best way to solve the problem based on the information present.

Here’s an example of a problem I’ve given in the past:

1) The time it takes a car to attain a speed of 30 m/s when accelerating from rest at 2 m/s2 is      

A) 60 s.

B) 15 s.

C) 30 s.

D) 2 s.

I’ve expanded it into some basic steps to make the process visible:

1) A car to attain a speed of 30 m/s when accelerating from rest at 2 m/s2.   The given quantities are     

A) starting velocity

B) final velocity       

C) time

D) acceleration

E) displacement   

 2) The time it takes a car to attain a speed of 30 m/s when accelerating from rest at 2 m/s2 can be found using

A) a = (vf - vo)/t

B) x = v0 + ½ a t

C) vf2 = v02 +2ax

3) The time it takes a car to attain a speed of 30 m/s when accelerating from rest at 2 m/s2 is      

A) (0 m/s - 30 m/s) / (2 m/s2)

B) (30 m/s - 0 m/s) / (2 m/s2).

C) (2 m/s2) / (30 m/s - 0 m/s)

D) (2 m/s2) / (0 m/s - 30 m/s)

4) The time it takes a car to attain a speed of 30 m/s when accelerating from rest at 2 m/s2 is      

A) 60 s.

B) 15 s.

C) 30 s.

D) 2 s.

By making each question an equal step, it helps to highlight the intentional thought process required. Too often, students tell me that they can do the problems as long as I tell them what formula to use.  But, that’s missing the whole point.  The selection of the correct tool is what I’m trying to teach.  Not simply the plugging in of numbers into a calculator.

I imagine that at some point students will complain about having to go through these basics steps, but I’m hoping to slow them down as they attack a problem and ramp up to solving it rather than race to find the final answer.

Are you asking the right questions to get the learning you want?