This textbook was published to reflect the 22nd revised curriculum that will be newly revised starting in 2024.

Solving 10 problems in your head is more effective in building your math skills than solving 100 problems by hand.
Learning only calculation methods can develop 'calculation skills' but does not lead to 'mathematical skills'.
Just as calculations have principles and methods, each calculation has its own properties and there are relationships between calculations.
Additionally, children should be able to use calculations and develop number sense through calculations.
In this way, problems that allow for considering a single operation from various angles, rather than cross-sectional calculations, were designed based on mathematical design grounds to enable three-dimensional calculation training.

You can master elementary, middle, and high school math by doing math operations, not just arithmetic operations.
Since mathematics is a subject that is connected to elementary, middle, and high school, concept formation in elementary school affects learning in middle and high school.
Concepts learned in elementary school can be easily taken lightly, but they are connected to important concepts in middle and high school, so learning operations that can grasp their mathematical meaning is essential.
In addition, the mathematical rules learned in middle and high school should be experienced from an elementary school level, so that they can serve as the center of the entire mathematical learning.

Math concepts remain only after you think, solve, and feel them.
Calculating from beginning to end is not only boring for children, but also causes them to miss the mathematical meaning behind the calculations.
We created a three-dimensional learning structure so that calculation training can lead to understanding of mathematical concepts by allowing students to understand the mathematical principles on which it is based and the calculation methods that follow.
Additionally, the importance of the mathematical concepts contained in the problems and how they are related to secondary school learning are separately organized and included in the answer key.