Students' awareness of estimation is weak. The main reason is that in the long-term mathematics teaching, students have practiced more accurate oral and written calculations and formed their actuarial thinking mode. Some teachers are biased in the orientation of estimation teaching, aiming at only teaching estimation, or estimating when they see "probably", and doing some mechanical training may form a wrong formula for students, so that they can't fully realize the value of estimation in real life and mathematics learning.
2. Pay attention to the guidance of methods, realize the diversification of methods, and let students estimate creatively.
Although the estimate is an estimate, it is not a guess. It is not only a mathematical idea, but also a strategy to solve practical problems. The estimation methods are flexible and diverse, and the results are not unique, so the application of estimation methods has two purposes: first, the calculation should be simple and the approximate results can be calculated quickly; Second, the estimated results should be as close as possible to the actual results. Teachers need to guide students to feel and experience in comparison, and understand the profound connotation of estimation methods in comparison.
3. It aims at practical application and improving students' ability to solve problems.
The main purpose of cultivating students' estimation ability is to let students solve some practical problems in life with mathematical knowledge, which is also the intrinsic value of estimation. It is difficult to improve students' ability to solve practical problems simply by training mechanical estimation with formulas. Estimation is not as close to the exact value as possible, and different scenarios need different estimation methods. There are mainly the following situations: First, simultaneous estimates are sometimes reasonable. For example, "there are 350 students traveling, and there are 7 cars with 56 seats each." Estimated, enough? " Take 56 as 50. At this time, seven carriages can seat 350 people. Even if the number of people is estimated to be small, 350 people can still sit, so 56 seats per car will definitely be enough. Second, it is more reasonable to estimate the quantity at the same time. For example, "Mom brought 100 yuan, and she bought clothes from 48 yuan and socks from 12 yuan. Is this enough? " Think of 48 as 50 and 12 as 20. Even if these two figures are overestimated, the answer is 70 yuan, so 100 yuan is definitely enough. Thirdly, it is reasonable to make the estimated value close to the exact value. For example, when you pay for shopping in the supermarket, you need to estimate the money as close as possible to the exact value. You can estimate a large number and a small number. Teachers let students analyze with specific situations, which can not only help students learn flexible estimation skills, but also make them feel the significance and role of estimation in specific situations. Only by combining the teaching of estimation with the reality of life can we stimulate students' desire for estimation, enable students to actively acquire the methods and skills of estimation, and show the intrinsic value of estimation. Only in this way can students apply the book knowledge they have learned flexibly and consciously in real life.