1: On the phone, I realized that we need to divide by decimals to solve problems in life, and further understand the close relationship between numbers and life.
2. Using the existing knowledge and experience, explore that division is the process of fractional division calculation method, and experience the teaching idea of transformation. 3. Cultivate students' good ideological and moral sentiments and understand the application of fractional division in real life.
[Teaching Emphasis] The calculation method of fractional division with divisor as decimal.
[Teaching Difficulties] Determination of the decimal point of quotient.
[Teaching process]
First of all, review the old and learn the new.
Vertical calculation:
0.48÷4 6.3÷7 240÷60 4800÷400
Second, situations stimulate interest and explore new knowledge.
1, the courseware shows the situation diagram of the textbook, guiding students to find mathematical information and find mathematical problems.
Guide the students to find Xiaoxiao's and Naughty's phone numbers and make domestic long-distance calls with Xiaoxiao. 0.3 yuan per minute, * * * fee 5. 1 yuan; Naughty international calls, 7.2 yuan, * * * 54 yuan every minute. Who has been on the phone for a long time?
2. first estimate who has been calling for a long time.
1. Discuss in groups how you estimate; ② Report the estimation process in groups; ③ Evaluate and encourage the rationality of evaluation methods.
Students' estimation methods may appear as follows: ① The call volume per minute of international long distance in 7.2 yuan is about 20 times that of domestic long distance in 0.3 yuan. If Xiaoxiao and the naughty boy talk at the same time, the total phone bill of the naughty boy should be more than 20 times that of Xiaoxiao, but 54 yuan is about 5.65438+ 10 times that of 0 yuan, so Xiaoxiao talks for a long time; 25.1is about a dozen 0.3, so it takes more than ten minutes to make a phone call with a smile, and there is no 10 7.2 in 54, so the naughty phone call is definitely less than 10 minutes, so it takes a long time to make a phone call with a smile.