Where in real life are you required to have the answer to every problem or question on the tip of your tongue at a moment’s notice? Even doctors and lawyers must do research and use reference materials: they are not required to know everything at all times. Contrariwise, a worker (at any kind of job/career) who has no idea where to begin looking for an answer to his problem will not have a very promising future. Therefore, teaching our children how to use reference materials and how to do problem solving are the greatest skills we can impart.
I taught some history/geography classes in our homeschool co-op group that were run game show-style. The students were given lists of facts ahead of time that they would need to know in order to answer random questions, but they were also told that they would be allowed to refer to those lists during the game. I gave them brief instructions on how to read through the material and highlight keywords. It was fascinating to see how these middle-school-age scholars took to the concept! When they showed up two weeks later to play the game, their notes were appropriately marked up, they dived into the stack of papers with enthusiasm when a question was put to their team, and they knew exactly where to find a remarkable amount of facts in a surprisingly short period of time.