In a larger sense, in reading music there are only three choices. A note is “on a line,” “on a space,” or “on the little line,” or Middle C.
It may take years for a child to arrive at control of this “game.” There are hundreds of permutations of “on a line,” or “on a space.” For example, which line? Which space? There are dozens of each!
The best way is to acquaint the child with the idea of five lines. After that, find the lowest of the five lines and get control of finding that. Then you must find Middle C, a separate study in itself. Lastly, the child must be able to find and distinguish the spaces in between all the lines.
Now perhaps you won’t wonder why reading music is so hard for kids -- It’s difficult for most adults!