In high school, I had a calculus teacher who said to our class, "Half of you hear half of what I say half the time."
He said it often.
Maybe he was reacting to our dumbfounded looks as we gazed at the complex derivatives on the board. Or maybe, he was on to something.
I don't remember much from that class. In fact, the only other vivid memory I have is a poster near the entry to the classroom. It was a visual landing spot whenever my mind wandered.
The poster was a quote from behavioral psychologist B.F. Skinner. It read: "Education is what survives when what has been learned has been forgotten."
For what little I recall from senior calculus, what survived was two important reminders I now use when giving feedback to an athlete or team:
Be concise
Repeat what's effective
Many coaches (myself included) say too much and repeat too little. When we say too much, it's hard to know what to remember. When nothing is repeated, it's hard to know what to value.
Be concise.
Repeat what's effective.