In the comments, say something. If you’re looking for a prompt, how about “Give a theory as to why this kid made the mistake that he did.”

  • This student is enjoying the benefits of our wonderful notational heritage. Writing things next to each other, or outside parentheses means multiplying. We said f = 2x and g = x-4, and if you substitute those literally, you get the student’s initial step precisely. It’s interesting that they distribute for the first problem but not for the second, and includes the (x) as a variable in the 2nd but not in the first.

    @delta_dc and I like the Vygotsky can/approximating/not yet bullseye for evaluation. The student can substitute, is approximating distribution of one term over two, and is not yet understanding function notation.