When I taught notetaking to my son, now in 7th grade, I showed him visuals using the bullet point system.
For example, say you are studying elephants, tell your 3rd grader to label what a question might be about, i.e...
Weight - How much do elephants weigh?
Height - How tall are elephants?
Food - what do elephants do elephants eat?
Herbivores - what are herbivores?
Activities - What do you see elephants doing during the day? nite?
Walking - why is it important for an elephant to walk?
Dusting themselves with dirt? Why is that important?
etc. They begin to see the catergories and then sub-categories that come along with any topic. Also, when it's outlined in this manner, it's easier to go back and find the answer to a question, based on which category it would fall in.
My son also incorporated drawing a line a little left of center down his paper, that gave him a box to write everything he knew about the subject that was on the right hand side of the line.
By 5th grade, he was actually being complimented by his teachers for his organized note taking skills.
This type of bullet system works great for any subject matter; math, english, language, foreign language, etc.