I asked students to write about what forces must be balanced when a box is pushed across a floor at constant speed. Here is what one student wrote.
At a constant speed, the force of gravity pulling the object down must balanced the force of the floor pushing the object up.
Same student responds to what was confusing about the reading:
Do balanced forces have to be equal or “canceling out” forces? In the first question, if I’m constantly pushing the object at the same speed then the my force on the object is higher then the force of friction on the object. but my force stays constant and the lesser force of friction stays constant. I wanted to add this to my anwser on the first question but was a bit confused.
This is so important. The first question invoked in this student a response like, “Get down a correct thing you read from the text, and don’t risk getting it wrong by putting down what you actually think.” The second question invoked a different response, more like “Tell the instructor what you are really thinking and ask a question about how that thinking relates to the reading.
As instructors, these are some question we should always be thinking about: How are our students framing tasks of responding to the questions we pose? Are they looking to get correct stuff down and avoid getting incorrect stuff down, or are they honestly engaging in a dialogue between their ideas and the ideas they are encountering. How do we know whether its one or the other? How do support a culture of the second?
Teach. Brian. Teach. 
I don’t really think this is the case, but I’m curious what you think about it: Could it be based in a vocabulary problem? Words like “balanced” or “forces” might not yet be fully owned by students and so when they’re asked about them, they give textbook answers instead of personal ones.
I don’t think you are wrong. I think there are lot of factors that can influence students’ conscious or subconscious decision of how to respond to questions, and I think that the vocabulary must have some effect. It sends a signal about what “kind” of question is being asked… is it a question about “your thinking” or a question about “textbook answers”.
Andy, I don’t know if you’re right or wrong about students “owning” the vocabulary, but to me it is obvious they don’t own the concepts, which is the point of going through the learning process, in my mind.
But what is interesting to me about this specific case of vocabulary is the use of balanced/unbalanced to describe forces. I had somehow thought this terminology had fell out of favor by physics teachers in the last 10-15 years. But, in the past 6 months, I’ve seen it more than ever. I rarely use these words to describe force pairs in class. Instead, I talk about the sum of all the forces. I used to use “net force,” but stopped doing that when it became apparent that some students might think “net force” was a single type of force acting on the object rather than the vector sum of all the forces. Would my students be better off if we were using the “balanced/unbalanced” terminology more?
Brian, do you think that this student (and those who answer similarly) are still in the “buy in” phase of accepting that this class is a little different than previous classes they’ve had? I mean, do you think that later in the class these same students will have made the leap from thinking there is a dichotomy of frameworks that you’ve identified to just accepting that they can be honest about what they are thinking versus what the book says? I try very hard at the start of each semester to make the point with my class that trying to read my mind is an exercise in futility. (See, there’s nothing in my mind, so it’s pointless to try to read it.) That is part of how I try to get the class to think deeply and honestly for themselves, and not try to guess what the “book answer” is.
So just to be clear, the responses here and the questions are for a reading quiz, so I don’t expect students to own the concepts, at least not now. Another thing is that this class is very traditional in some ways, especially with respect to content. This is true despite some interactive engagement activities (clickers, white-boarding, etc).
I think the fact that this student is willing to show me the dichotomy is a very good sign. The dichotomy is readily available for me to see, and the student is at least willing to share their ideas when I give them an opportunity, and they are willing to be expose themselves. There’s a vulnerability in sharing what you think, especially when you think you might be wrong.
I’d be more worried if there wasn’t a visible sign of the dichotomy, because students could be privately not engaging their own ideas at all (just trying to memorize physics facts, or having ideas that they think should be kept private (at all times) from the instructor.
I expect that if I’m doing a good job, students will (1) try to understand physics content in relation to their own ideas and experiences AND (2) feel comfortable sharing their ideas and their struggles with me and the class.
Brian,
Have you ever thought of showing both of these responses to your class and having a discussion about the different levels of feedback?