Prof, I taught that way for a couple of reasons ...
"Always/Never, Keep and Know" was the mnemonic device .... I found it was easiest for them to retain.....
...and "Always" is always ..... even if you are not holding the gun: if it's laying on a table, you don't stand in front of the muzzle .... you don't put it down where it can fall (and possibly discharge) ...... "Always is Always" .....
.... "Never" ..... see above ...... and "Always" and "Never" are easily associated words, and closely related.
Now that we can pick up the gun, because it's loaded (They always are, in our minds, right?) but that's OK, we are not standing in front of it .... and we know we can't point it at anything we don't want holes in ..... we can pick it up properly ..... with the index finger straight, preferably on some indexing point that we are going to habitually use with this gun every time..... *
...now we can identify the target, and what is behind it..... even if we hit it, we know bullets go through things...... are we good? Can we shoot now?
One of the things I did in class was have the kids bring in news reports of firearms "accidents" each week ..... and have them list rule violations. IIRC, we called that segment "Stuff Happens. Make sure it does not happen to you."
*the kids always yelled at violators if the finger on the trigger rule: "Get your booger hook off the Bang Switch!!!!!!"