The difficulty ranking of primary school mathematics teaching AIDS can be different according to different grades, versions, publishers and regions, so it is difficult to provide a unified ranking. In addition, the difficulty evaluation also varies according to students' individual level and school curriculum requirements. However, the following are some popular elementary school mathematics teaching guidance books, which are usually considered challenging and provide good mathematics exercises:

People's Education Publishing House's synchronous exercise book for primary school mathematics: a supplementary book published by People's Education Publishing House, compiled according to China's primary school mathematics teaching standards. These workbooks usually provide a wealth of math exercises, covering various topics of all grades.

The elementary school mathematics exercise books published by Beijing Normal University Press are very popular in primary schools all over China. Their math exercises are usually designed to be interesting and challenging.

Oxford elementary school mathematics workbook: a supplementary book published by Oxford University Press, which is suitable for different international elementary school mathematics courses. They usually pay attention to the cultivation of mathematical thinking and problem-solving ability.

Teaching materials for remedial classes: The teaching materials published by some remedial classes and training institutions are often challenging and suitable for students to expand their mathematics knowledge after class.

Teaching aids for competitions: The teaching aids for mathematics competitions and Olympic Games are usually challenging and suitable for students with special interest and talent in mathematics. Please note that the choice of teaching AIDS should be based on students' grades, abilities and school curriculum requirements. Sometimes, schools or teachers may provide suggestions to help parents choose suitable teaching materials.

In addition, understanding students' learning styles and needs is also an important factor in choosing appropriate teaching AIDS. In the end, one of the goals of choosing teaching AIDS is to make students feel challenged at an appropriate difficulty, but not too depressed.

Characteristics of sunshine students (taking mathematics as an example);

(1) The learning content of each example in the textbook will correspond to an interesting math reading story, which can effectively help students consolidate their math knowledge, stimulate their interest in math learning, broaden their math horizons, and enhance their math core literacy.

(2) Every interesting math story is followed by a corresponding "math coup" to facilitate and guide students to sum up the key points they have learned, and to help and improve students' effective reading, mathematical thinking method refining and math self-study ability.

(3) The real situations and sci-fi stories in mathematical story materials are flexible and changeable.

(4) The presentation is novel and interesting, with reasonable gradient and moderate difficulty.