Ensuring children's understanding by introducing new ideas
through the chapter named "Think About How to Calculate":
For developing children's problem-solving skills in multiple
ways, some chapters have the previous pages named "Think
About How to Calculate,'' aiming to teach children to think
about how to calculate, not the specific way of calculation itself.
Through this preparation, children are able to relearn how to
use what they have learned before and apply their ideas to
unknown situation with necessary representations. This relearning
is the preparation for the next chapter. Without this
preparation, many children forget what they have learned
before, which is necessary for the next chapter.