I'm sure this is not ground breaking news. For those of you with 2 or more children, you've probably already found this concept happening in your home. People often don't understand how I can teach 3 (soon to be 4) different grades at the same time. Although this year has been the most challenging for me, one of the things that has kept me afloat is letting my older children help teach the younger ones. The best part about this philosophy is most of the time, my kids don't even know they are learning. They enjoy "playing" school and my oldest is usually the teacher.
I have noticed a number of times where I have gone to teach one of my younger children a concept and they already knew how to do it because their big sister had told them. This has even happened with my 3rd girl. One day she excitedly called me over to show me that my 3 year old had written a "J". I smiled that smile of, "Oh, how nice (not really believing he did it)". Well, to my surprise, he had not only written a "J" but an "A" and "E". I have never even tried to write any letters with him before.
I guess learning from your big sister must be a lot more fun than learning from boring old mom. That's ok, it works for me and I am loving it.