Learning "Understanding of Clock" in the second grade of primary school mathematics is both important and difficult. The teaching content of this lesson is mainly to guide students to know, read and write the whole time in observation and comparison, to feel the connection with life in the process of learning mathematics, to guide students to feel the preciousness of time and to educate students to cherish time.

Conversion relationship of time units:

(1) One day = 1440 minutes, 1 hour =60 minutes, 1 minute =60 seconds.

(2) A moment = 15 minutes, and a word =5 minutes (used in southern Fujian and Guangdong).

Angle relation of each pointer of the clock:

(1) An ordinary clock is equivalent to a circle, and its hour hand or minute hand is equivalent to walking 360 degrees.

(2) The angle of each large grid on the clock is 30.

(3) Every time the hour hand passes 1 min, the corresponding angle should be 0.5.

(4) The angle of minute hand per 1 min should be: 6.