What do you think of middle school students' innovative chemistry experiments? Urgent need! ! ! ! ! ! !

Chemistry is an experimental science, and experimental ability is an important part of students' scientific literacy. In order to strengthen experimental teaching and improve students' experimental innovation ability, educators have worked hard for many years. Teachers' experimental quality is the key to strengthen experimental teaching. This paper talks about my own feelings from the teacher innovation experiment contest held in our county, and puts forward some improvement attempts to discuss with my peers.

"Chemical experiments are the basis for the formation and development of chemical science and the standard for testing the truth of chemical science knowledge; It is an important medium and means for students to gain chemical experience and test chemical knowledge in chemistry teaching, and it is also an important content and way to improve students' scientific quality. "It has become the knowledge of all chemistry teachers to carry out chemistry teaching based on experiments. So how can we give full play to the role of experiment in chemistry teaching, make chemistry experiment teaching more in line with the trend of teaching reform and meet the needs of quality education and innovative education? Only by continuous improvement and innovation can chemical experiments be full of vitality and maintain its unique charm in chemistry teaching.

There are many ways to innovate in chemical experiments. Teachers should learn how to choose innovation points, that is, learn to find out where the innovation points are. The author was lucky enough to experience the third middle school chemistry innovation experiment competition in the county, and was deeply touched. Now I'll take one or two of them for readers.

First, the characteristics of chemical innovation experiments

Where is the development direction of chemical innovation experiment in middle school? I think the key is to embody the word "new", keep pace with the times, innovate constantly and give full play to the experimental function with high quality. Below I will list a few highlights of this activity, hoping to play a role in attracting jade.

1, transform the experimental instrument to make the operation simple and easy.

We are used to using traditional experimental instruments in teaching, although it will bring good results, but we often ignore the clumsiness and caution of the instruments. This idea of taking classics as authority is often the crux of teachers' lack of innovation. In fact, scientific experimental methods should constantly find problems, and the shortcomings of traditional instruments undoubtedly provide us with experimental innovation topics.

For example, in the "material heating" experiment, people have become accustomed to using an iron frame (with iron clips) to hold test tubes. Considering that the iron frame is bulky and inconvenient to use, a device as shown in figure (1) is designed. The improved instrument is simple, easy to obtain materials and easy to carry. In addition, some people have designed a simple "safe alcohol lamp" according to the unsafe factors in the use of alcohol lamps (see figure 1).

For another example, when studying the section "Law of Conservation of Mass", when weighing the mass of sodium hydroxide and copper sulfate solution before and after the reaction with a tray balance, the operation is complicated and the intuition is not strong, so the device shown in Figure (2) can be designed by using the buoyancy principle to observe and compare the immersion height of the test tube before and after the reaction (the test tube is marked). The improved experiment is convenient to operate, and at the same time, it also improves students' interest in learning, which reflects the integration of disciplines.

2. Transform the experimental device to reflect the "greening" of chemical reaction.

For a traditional experimental device, its feasibility is beyond doubt, but there are more or less some shortcomings: for example, there are many connected instruments, which are inconvenient to operate; Long reaction time is not conducive to teaching; Produce toxic tail gas, which is harmful to human health; Wait a minute. In order to innovate and reform experiments, these should be considered.

For example, when teaching "combustion conditions", if red phosphorus and white phosphorus are directly burned in the air, it will not only pollute the environment, but also endanger health. If conditions can be created for the experiment to be completed under closed conditions, the above shortcomings can be solved. Figure (3) is the "green" design of the experiment. The specific methods are as follows: ① Squeeze the air pump to introduce air, and there is no obvious phenomenon (indicating that although the combustible is in contact with oxygen, it will not burn until the temperature reaches the ignition point); (2) Preheat the test tube evenly with alcohol lamp, then focus on the middle part of red phosphorus and white phosphorus, and squeeze the air pump at the same time (make the air pass through red phosphorus first and then white phosphorus). At this time, white phosphorus can be observed to burn violently without obvious change, which can prove the combustion conditions. The biggest advantage of this experiment is that it is completed in a closed condition from beginning to end, which is beneficial to environmental protection and symbolizes the requirements of green chemistry.

Another example is the experiment of measuring the volume fraction of oxygen in the air. Because the airtightness of the experimental device provided by the textbook is not easy to control, and there is still air in the airway, the following improvements can be made: put enough white phosphorus in the test tube and plug it, heat it with alcohol lamp to make the white phosphorus burn fully, immerse the test tube in water after cooling, take out the rubber plug under the water surface, then plug it, and then take it out to observe the water surface later (put 5 equal test tubes in advance). This experiment has few instruments and good effect.

3. Design solutions for potential safety hazards in the experiment.

In some experiments, it is often difficult or even dangerous because of the special chemical properties of substances. Most teachers avoid talking about it, or just tell students the principle. As we all know, these experiments are rich in innovative materials, which can well cultivate students' creative thinking ability.

For example, it is difficult and dangerous to do the flour explosion experiment in the last edition (ninth grade) textbook. If we try our best to overcome difficulties and let students complete experiments in a safe and curious state, we can not only deepen their understanding of the experimental principle, but more importantly, we can eliminate their fear of experiments and cultivate a scientific concept of "experiment". Figure (4) shows the improved experimental device: in the experiment, the ear washing ball is used to suck flour, the candle is lit, the lid is closed (not too tight), and then the ear washing ball is squeezed hard to make the flour fill the whole container, and the lid is opened with a bang, and the teaching task is successfully completed with cheers.

4. Design interesting experiments according to the chemical properties of substances.

In teaching, some interesting experiments can be designed according to the particularity of material chemistry, which can not only enrich the classroom content and consolidate the knowledge learned, but also improve the interest in learning and stimulate students' curiosity.

For example, according to the nature that carbon dioxide can neither burn nor support combustion, an interesting fire-fighting experiment can be designed: first, collect a bottle of carbon dioxide gas, then ignite the cotton sliver dipped in alcohol and put it into a gas container (be careful not to put all the cotton sliver into the bottle), and you can observe that the part immersed in the bottle goes out, and if the cotton sliver is taken out, it will resume burning. Through this simple experimental design, students' thinking sparks also shine on the paper.

Second, the reflection on experimental teaching

Although this activity has been well received by the leaders and teachers attending the meeting, it has played a very good role in the reform and innovation of chemical experiments, but some problems have also been exposed in the experiments, such as insufficient innovation and exploration, and some experiments are biased towards the development trend of "high, large and long" ...

Experimental teaching reform of new curriculum standards plays an important role in chemistry curriculum reform. Teachers' ideas, attitudes and reform efforts will directly affect the teaching quality and educational effect of the whole new textbook. Teachers should take every experiment seriously, inspire and guide students to pay attention to the experimental process, highlight students' dominant position in experimental teaching, strive to stimulate students' interest in learning and enthusiasm for inquiry, and strengthen the feedback and evaluation of students' learning effect in experimental teaching.