I have long held the idea that older people ("wrinklies") seem to take longer to learn for a very good reason. They do. But they do for a very good reason, too. My hold on this idea has become stronger as I have grown older. Probably not mere coincidence either.
At the heart of my thinking is the concept of cross-linking information. A new piece of information is linked with existing information; cross-indexed, if you like. The more information you have, the more cross linking needs to be done to "fully absorb" the newer stuff. If you want understand it, that is. For example, if you were to tell a younger child you were going to get some new clothes, and that those clothes would be blue, the child could easily accept and understand. Say the same thing to an older child and the linking might kick in more obviously - what clothes? who for? will the blue match existing colours? will they be fashionable? An adult might well start wondering about how you could afford the clothes, what advertising influences you were the victim of etc. Some even older folk - wrinklies, even! - might end up thinking (and telling you) about the difference that the chemical engineering industry made when it produced the first stable blue dyes. But note, some of these questions are likely to crop up some considerable time after being given the original information.
So be patient as you teach older folk new things. Don't be surprised when they seem reluctant to share your enthusiasms. Don't be surprised either when they sometimes end up with a better grasp of what you have said then you have yourself...