Teachers point out "mistakes" in 10th grade exam

Mr. Mai Van Tuc, a physics teacher at the High School for the Gifted in Natural Sciences, Hanoi University of Natural Sciences, pointed out some issues about question 5 in the 10th grade math exam, related to physics knowledge as follows:

The problem gives a law of power loss in the process of boiling water that does not occur in reality and is incorrect in nature. The process of energy conversion when boiling water is calculated from the moment the switch is turned on (at t = 0); electrical energy is converted into heat energy, making the heating wire hot (if the kettle uses a heating wire). The heating wire has a higher temperature than the water in the kettle and transfers heat to the water, the water transfers heat to the kettle and there must be a period of time for the temperature of the kettle to increase higher than the ambient temperature for there to be heat loss to be released into the environment. The power of heat dissipation to the environment depends mainly on the contact area of ​​the kettle with the environment and the temperature difference between the temperature of the kettle and the environment (the power loss also depends on the level of air circulation or wind in the place of heating). When the power of heat dissipation to the environment of the kettle is equal to the power of receiving electricity of the heating wire, the temperature of the water will no longer increase.

It can be understood as follows: A heating wire with a capacity of 1,000W, if heating water in a 2-liter kettle, the water can boil, but if this heating wire provides heat for a large fish tank, the water can only heat from 100 degrees Celsius to 300 degrees Celsius and then stop increasing in temperature. So question 5 gives the power loss according to the rule P = at + b, meaning that at t = 0, the power loss is equal to 85W and the power loss increases steadily, which is wrong (I ignore the confusing errors).

In addition, in point b) of question number 5, the writing question is: If boiling water with a power loss of 105W, how long will it take?

"In my opinion, that is wrong. If we assume that there is an illogical rule as the author suggests, we should ask: Calculate the boiling time until the power loss is 105W. Instead of writing 'If the water is boiled with a power loss of 105W, how long will it take to boil?', it shows that the author does not understand anything about physical phenomena and the reader does not understand how to calculate it," said the above teacher.

In addition to pointing out the "mistakes" in physics knowledge applied to practical problems, the above teacher also suggested that the HCM City Department of Education and Training should adjust the answer to question 5 to be fair to candidates. Many candidates who are good at physics will not be able to do question 5 because some candidates said that physics knowledge is too "strange".

At the same time, Mr. Mai Van Tuc commented: "First of all, I appreciate the idea of ​​applying math to life of the group of test authors. However, when applying math to reality related to knowledge of other fields, we need to be very careful because in my opinion, in addition to an exam for admission, this is a very focused self-study session for the test takers."

Therefore, whether passing or failing, the exam must have content that after the exam, the participants will gain more or less knowledge. And when using scientific knowledge, it must be accurate, science exists completely objectively. Every subject must be accurate, there is no such thing as math understood in one way and physics in another, Mr. Tuc stated his opinion.

Ho Chi Minh City Department of Education and Training responds to 10th grade exam questions

Regarding teachers' opinions and suggestions on the 10th grade math exam, Thanh Nien Newspaper reporters had a discussion with the leaders of the Ho Chi Minh City Department of Education and Training and this agency gave an official response.

Regarding the opinion that the content of lesson 5 of the 10th grade math exam contains errors in physics knowledge, the Department of Education and Training responded as follows:

The problem presents content related to the real phenomenon of the process of boiling water in an electric kettle (a familiar item in many families). This survey process is only a short stage of the water boiling process; the starting time of the survey (t = 0) is not the starting time of the water boiling process. The data are described mathematically by a drawing and a function that students have learned in the program. With the knowledge of: first-degree functions, graphs of first-degree functions, points on the graph, systems of first-degree equations with two unknowns, calculations... and their mathematical ability, students can solve the requirements set forth by the problem.

Mr. Nguyen Bao Quoc, Deputy Director of the Ho Chi Minh City Department of Education and Training, added: "During the exam marking process, according to general regulations, cases where students have solutions that are different from the marking instructions but reasonable will be considered and evaluated. The Department of Education and Training always appreciates comments on the 10th grade exams to improve the organization."