Is "PLEASE REMEMBER TO PARTIALLY CLOSE THE SHARPS BIN" supposed to be an example of doing this correctly, or incorrectly? I find the notice unclear, but it's also unclear what point the author is trying to make by using this image.
Seeing that sign without further context, I assume this is a bin full of sharpies (could be wrong), and that it is supposed to be left slightly open. How closed "partially" closed is I would have to guess.
But if this is for a group of students in an art class that have all been clearly instructed how to handle this bin (see "remember to"), it might be the perfect reminder. Meaning "Close it to the degree you've been shown in the first lesson".