The functions of diagnostic evaluation include: checking students' learning preparation; Decide on the appropriate placement of students; Find out the reasons for students' learning difficulties.

The role of formative assessment is: to promote students' learning; Set the rhythm for students' learning; Strengthen students' learning; Give feedback to the teacher.

The functions of summative evaluation are: evaluating students' academic performance; Prove the degree and ability of students to master knowledge and skills and the degree of achieving teaching objectives; Determine the starting point of students' learning in the subsequent teaching activities; Predict the possibility of students' success in the follow-up teaching activities; It provides a basis for formulating new teaching objectives.

Test difficulty and evaluation focus:

Diagnostic evaluation often adopts specially compiled tests and observations, and records and analysis of students' school records. The difficulty of the test questions is low.

Formative evaluation often adopts formative test, homework and daily observation to evaluate; The difficulty of the test depends on the goal.

Summative evaluation is often evaluated in the form of examination; The test questions are moderately difficult.