Kudinov V.V.

Chelyabinsk Institute of Retraining

and Improvement of Educators Professional Skill, Russia

Experimental tasks and exercises

in propaedeutic course in physics

Using experiment in the process of teaching physics solves different functions. In the form of demonstration experiments it serves as a source of facts, knowledge about the world, a means of developing interest in physics, especially in its earlier study. In the form of frontal laboratory work and physical workshop, it is a means of organizing independent operations of students, facilitate the acquisition of skills to apply the theoretical knowledge in practice.

One of the ways to implement the link between theory and practice is solving the experimental tasks and experimental exercises.

Classification of physical tasks can be performed on different basis – components of posers and the solving systems.

We offer classification of experimental problems and tasks by time of their use in educational process and by their relation to studying this or that theme of a course of physics. Peculiarity of the given classification is that at its drawing up we started with ideas of advanced studying of signs of physical concepts at the propaedeutic course of physics and organization of process of teaching physics in 5–6 classes according to the laws of empirical knowledge.

In line with this, we consider the following types of experimental tasks and exercises:

– the advanced;

• the previous;

• the perspective;

– the accompanying;

– the completing.

Let's consider each kind of exercises and tasks in detail and give the appropriate examples.

Advanced experimental exercises and tasks allow entering a new concept, to specify its essential signs. For their performance students have insufficient theoretical information, therefore the teacher should be guided by existing life experience, or use the method of “throwing the hook in the future”, allowing to receive answers to some questions at studying of following themes of a course.

We can distinguish two groups of advanced tasks. Experimental tasks and exercises allow to lead-up students to comprehension of features of a new concept, the study of which is expected on the following lesson, will be called the previous. And the exercises and tasks, that allow lead-up students for mastering features of new concepts, studied in the following topics of physics course, are called the perspective.

As an example of the previous task in 5 class can serve the following task in studying the topic “The motion of the particles of substance”. Put a piece of slate pencil or a crystal of manganese at the bottom of the glass with water. Observe, without shaking up. What kind of phenomenon you are observing? How can you speed it up? Formulate conditions at which you observe the diffusion phenomenon. Whether there will be observable diffusion phenomenon if you shake up a liquid? The use of such tasks in the classroom allows introducing the concept of diffusion as the spontaneous mixing of substances in the course of its implementation. A significant feature of the concept of diffusion – “spontaneous” mixing, in fact, derives from the condition of the task, which says that we should observe “without shaking”. Thus, if the students themselves mix water and crystal of manganese, they will observe a forced mixture of substances, rather than diffusion. This gives an answer to the second question of the task. Since our intervention interrupts the observed phenomenon, the students confronted with the following question – how to speed it up?

There is the following task in studying the topic “Body mass” in 5 class. How by means of a rubber plait it is possible to define, what of two toy carts has the big mass? If possible, do the experiment. The solution of this task at this stage will bring the students to introduction of the concept "gravity" and "strain" and "strength of the elasticity". This problem can become and a starting point in consideration of a question on a point of application of force, its direction and size (module).

In studying the topic “Power. Measurement of the force dynamometer” the following experimental task is offered to students. Put on a table a piece of foam rubber and drop on it a plasticine ball from height of 30-40 cm. What changes occur to a ball and a foam rubber piece? During performance of this task students observe that at ball falling on a foam rubber surface last bends, i.e. it is deformed. Students establish the fact that action of force is the cause of deformation of bodies, but cannot name yet, what force has caused this deformation. Students can find the answer to this question only in the following paragraph. In the same task one more “riddle” is covered. Why foam rubber restores or nearly recovers its shape (depending on type of foam rubber student or the teacher selected)? As already it has been noted above, students will learn about force of elasticity later.

The foregoing exercises and tasks play an important role in learning physics. They can be carried out in a class or at home, thus it is possible to tell that home experiment in this case is preferred. Having executed it and having answered task questions, the pupil prepares for the realized perception of a new material. He has an opinion on the causes of the observed phenomena, and hypotheses about its nature. At a lesson the exercise carried out by pupils is analyzed before studying of a new material. On the ground prepared in this way interest to a studied material essentially increases.

Let's result one more example of the previous task offered before studying of a topic «Temperature and its measurement. Thermometers».

«The device for temperature measurement – the thermometer – you’ve always known. You saw the mercury medical thermometer, spirit thermometer for measurement temperatures in a room and behind a window. Perhaps you have seen bimetallic thermometers, which sensing element is a twisted like a spiral of long and thin plate, consisting of two metals. How they work? To understand it, we will make model of measuring element of a bimetallic plate.

Cut out from a paper a strip in width of 2 cm. and in the length 19 cm. Fold it so that one side was 10 cm long, and the second - 9 cm. Glue free ends of the strip.

Folded before gluing:

Why the glued strips bend? How can you increase the bend?

Here is an example of the perspective task. Studying gravity, students are offered to observe changes of speed or the form of the body which are on a support or pendant, by gravity. Such task, on the one hand, allows realizing that all those signs which have been allocated for all forces are inherent in gravity. On the other hand, prepares for studying of one of most difficult accessible to students concept of weight of a body.

The accompanying exercises and tasks are experimental ones, on the basis of which it is worked out essential features of the concept, its content, as well as going to its mastering by students. Such exercises and tasks are considered directly during studying of the given concept, the phenomenon or process.

Let's give examples of such exercises and tasks.

In 5 class at studying a topic “Gravity” the following task is given. Measure gravity operating on the weights in weight 100, 200, 300 gramme. You have noticed what dependence? Performance of the given task fulfills skill of work with a dynamo-meter, measurements of gravity by means of a dynamo-meter. It is important to establish experimentally the fact of directly proportional dependence between weight of a body and gravity operating on it in this case.

In 6 class at studying the topic “Constant magnets” students should carry out the experimental task of the following maintenance. Study a magnetic field of permanent magnets. You will need a strip magnet, the magnetic needle, ring magnet, horseshoe magnet, steel wool and a sheet of paper.

This task is aimed at working out concepts “magnetic field”, “magnetic lines” and allows to draw conclusions on how magnetic field lines look like, how the form of lines of a magnetic field depends on the magnet form and how density of magnetic lines depends on distance to a magnet.

The completing experimental tasks and exercises establish relations with concepts fulfilled earlier; practical application of the received knowledge can be used as tasks for fixing the researched topic, revision, realization of inter-subject communications.

Let's give an example of a problem offered after studying of a topic “Float of bodies”. It allows repeating and generalizing knowledge of a gravity and Archimedes force, of substance density.

The test tube with a plasticine piece is in water. Whether depth of immersing of a test tube if plasticine to take out and glue to a bottom will change? If will change, how? Try to explain the answer.

The given classification allows considering a role of experimental exercises and experimental tasks in formation of physical concepts at students in the conditions of early training to the physicist.

Let's notice also that the offered classification of experimental exercises and tasks on their usage time in educational process and on their relation to studying one or another topic of a propaedeutic course of physics is conditional. Depending on the training and methodical complex chosen by the teacher the same exercise or the task can concern different types in offered classification.

Nevertheless, use of the given classification in preparation for a lesson or a choice of its maintenance will allow the teacher to define unequivocally a place of each exercise or the task at studying one or another topic of course of physics and a propaedeutic course in particular.

Use of experimental exercises and experimental tasks in educational process allows solving various problems. Carrying out experimental exercises and tasks brings up at students aspiration to active knowledge of the world, ability own forces to extract knowledge, promotes reception by students of strong intelligent knowledge, formation at them ability to use this knowledge in practice, in a life.