Immediately after class, as the lunch line swells.
Student: Can you show me that cross-product/torque thing again?
Cornally: Sure, what about it?
Student: I just don’t get the math.
Cornally: Do you want me to do another example?
Cornally creates two random 3-vectors and begins to find their cross product with the determinant of a 3×3 matrix. Student sits on a table and watches. Student listens to Cornally narrate, and corrects Cornally’s inability to keep track of negative signs.
Cornally: There are a few procedural things here, but what we’re trying to do is find a vector that’s ninety degrees to both of the first two, which is why the x-component only does math with the y- and z-components (drones on)
Student doesn’t take notes, just like he did during class. Cornally starts to become annoyed that he’s losing lunch time and Student isn’t even writing this down.
Cornally: …and so this result is ninety to both, and has a magnitude related to how perpendicular they were.
Student takes a picture of work with his high-res camera phone and texts it to the other students in his group. Student then leaves the room.
This kind of remediation is really common. I will often run little clinics during odd liminal times of the day. The students who get left off the Socratic train during class often just need a small piece of direct instruction that they can back-fill under the conceptualization.
I didn’t see the phone coming. I can only imagine how that student’s brain may have engaged differently if he had to copy everything I was writing while listening to me while hoping to go to lunch quickly.