What are some examples of “nix the tricks”-style shortcuts that are taught to students in physics?

I’m more interested in physics-specific ones, rather than generic math ones we happen to see in physics.

Also more interested in shortcuts we explicitly teach, less ones Ss invent

Example 1: Recently, I’ve heard some colleagues teaching students to remember that “acceleration vectors point from lower speeds to higher speeds” as a way to help them correctly identify direction of acceleration with 1D motion.

Example 2: I’ve been guilty at times of telling students that smiley face position time graphs will have positive acceleration and frowns face position vs time graphs will have negative acceleration.

What can be hard at times, I think, is to distinguish an appropriate early conceptualization vs a short cut understanding. An example: teaching that weight force points downward I think is appropriate, even if “toward center of earth” is the generally more powerful idea.

Anyway, curious what we can come up with. #iteachphysics