You can teach them through Bitcoin pictures by drawing or printing them from the Internet. But keep in mind that the images should be simple and clear. For example, draw circles or squares to represent Bitcoin, and an image of a Puzzle block or tree consisting of many small squares to represent Bitcoin transactions. Pictures often strike deep into the subconscious of children, but don't expect it to work and make them curious. After all, they are still children, expecting too much makes you become frustrated.
there are many ways to introduce things to children including bitcoin, basically children like to draw and color, we can easily find logos on the internet, and children are asked to imitate them, or maybe accompanied by cartoon characters first, so that it can continue remembering the child, or with a blank picture and the child is taught to color, and of course he is given an example of the color that should be used, of course he will ask what picture he colored.
They can only remember it as a shape and don't know what it is; this is like just going to draw the Bitcoin logo for fun and having color in it, but still the kid doesn't understand what it really is. Though the approach is good as they can remember it in the future, I think it is not the best thing to explain if they are still not interested or even understand it. They can better understand it if they watch videos, as they tend to get something from them. Though no matter what, if they are really at the exact age, they will for sure learn it, but as of now, it is better to let them do anything, draw, paint, and enjoy life as a kid.