The human brain can only handle a certain amount of information. And it is easiest for us to learn by association. That means that we build on our existing understanding. So for example, if we understand how to drive a car, it is easier for us to learn how to drive a truck. We have the “anchor” information already in our brain and we can attach new information to it easily.
Children’s brains are different. They are like giant sponges that soak up all the information that they can. Think about learning a language, such as French. As an adult learner, you will hear the phrase in French, your brain will translate it into English, you will think of the response in English and then your brain will translate in back into French. Children who have been exposed to French at a young age will not go through that process. They can think in French and English quite naturally.
So, when you are putting together a course, always try to “anchor” new information to something that your learners already understand. For example, “The material in the mill rotates like clothes in a washing machine”. The learning gets a quick and easy understanding of how it works without having to explain the principles of centrifugal force.
So, whenever you can, try and find an example of something that the learner would already know to compare to the new information. It will save a lot of time and it is much more effective.