Some people learn slow and remember forever. Don’t give up on them in week two.

Speed of learning and depth of learning are not the same measurement, though groups almost always reward the first. Someone who takes six weeks to get a thing often has it permanently, because they had to build the whole structure instead of copying the shape. Writing them off early costs you the most reliable person you would have had. It costs it invisibly, so nobody notices the loss.

If someone near you is behind right now, give it another month before you decide anything. Change how you are explaining rather than how loud. Ask them to show you where it stops making sense, and start there.