INFLUENCE OF AN EDUCATIONAL FILM ON THE EFFECTIVENESS OF TECHNICAL EDUCATION

Given its capacity to stimulate several senses simultaneously, the educational film triggers many paths of information flow during the learning process. Not only does it offer a diversified form of transmitting information, but it also makes the learning process more effective and attractive. This feature is particularly important in technical education, where the problems and issues discussed are often complex and difficult for students. The following paper contains an analysis of the impact of an educational film on the efficiency of technical education based on a pedagogical experiment performed on middle school students.


INTRODUCTION
Among the variety of teaching aids available, modern teacher should primarily focus on tools which, in addition to being an effective way of transmitting knowledge, enjoy popularity among students. Video films certainly belong to thosethey have been used in schools for many years already, and now see an educational renaissance thanks to the popularity of YouTube and other similar online video hosting sites [4,5].
An educational film is one of the most attractive forms of presenting learning content, easily attracting students' attention and keeping them interested for a long time [1,6]. The use of video elements allows the achievement of such goals in technical education as: • an introduction to the discussion of the issues raised in the film; • a change in the current form of presenting learning content, namely through showing examples of practical application of the issues previously discussed; • a summary of the subject at the end of the lesson.
The use of educational film in learning process, which constitutes an excellent audio-visual tool, enriches a lesson by allowing unlimited transmission and reception of information [7]. This type of film implements specific learning objectives and reflects the curriculum at all levels of education. Its structure, the means of expression used, the rate of transmission of information, the vocabulary used, etc. are all adapted to the features of both the subject and the recipient's capacities, in this case -the student's [2,5].
Educational film is structured on the basis of pedagogical principles and indications. Depending on its function, it can be used at different stages of the didactic process.
Several features of video aids determine their high suitability for the educational process [2]: • the film constitutes a visualisation of movement that can be watched at any place and time convenient for the user; • it allows viewers to observe uncommon situations and processes; • it allows transformations in time, reducing long-term processes or stretching out shorter phenomena; • all the viewers see the same content, while phenomena observed in nature may be perceived differently depending on the location of the viewer; • the analysis of the processes seen in the film stimulates the audience, allows drawing conclusions and solving problems; • visual information provided with a commentary is better received and memorised.
Educational video is usually addressed to a defined recipient, therefore, its preparation and creation should be carried out in accordance with established principles, including the identification of its objectives and the correlation of the content with the curriculum. Well considered and planned educational activities involving video aids should lead to: • increasing the students' technical knowledge; • teaching skills in working with different types of sources; • stimulating reflection on the subject; • undertaking independent research by the students.
Educational video currently occupies one of the leading places among many ways of illustrating lesson subjects. Therefore, it may be beneficial to explore the ways educational film influences the effectiveness of the learning process. By allowing visualising phenomena unobtainable or unachievable in direct observation, it helps to understand different processes and discover the existing correlations in both macroscale and microscale, and should therefore play a particularly important role in technical education.

METHODOLOGY OF RESEARCH
The aim of the study was to determine the influence of educational film on students' knowledge in one of the technical fields taught in middle school. A total of 52 students participated in the study. In order to achieve the aim of the study, the following research methods and techniques were implemented: • a pedagogical experiment, • an achievement test, • a chi-squared statistical test.
In the experimental group, an educational video "Soldering -construction and types" was shown during the lesson, while the control group only used textbooks. The students' knowledge was then verified in both groups by means of a multiple-choice test comprising eight questions. The number of correct and incorrect answers was counted. Due to the fact that students from both groups attended the same school, pursued the same curriculum and were taught by the same teacher, their level of knowledge prior to the experiment was assumed a priori to be similar.
In order to evaluate the variability of the number of correct answers in the test after multimedia lessons, in comparison to the lesson conducted with traditional methods, a coefficient K was introduced, described by (1): (1) where: y n -number of correct answers of students in the experimental group, y 0 -number of correct answers of students in the control group.
A chi-squared test was also used to determine whether the number of correct and incorrect answers depends on the didactic method used (i.e. the use of educational film). The variables tested were dichotomous by nature, so a bipartite table was used (Table 1) [3]. In order to determine the strength of the relationship between the variables, a coefficient r c was also introduced (4): (4) where: χ 2 -empirical value of the test, N -number of sample.

ANALYSIS OF TEST RESULTS
The results were presented in eight tables (Tables 2-9) and in graphical form as a radar chart (Figure 1).
On the basis of the formula (1), the coefficient K was calculated as 142.9%, meaning that throughout the test the number of correct answers of students in the experimental group was 42.9% higher compared to the number of correct answers in the control group.
In order to verify the independence of the features in accordance with the assumptions outlined in the methodology of research based on the data in Table 10, the empirical value χ 2 emp = 31.36 was calculated using formula (2). For the significance level α = 0.05 and the calculated number of degrees of freedom (formula 3) df = 1, the critical value was χ 2 tab =3,84. Because χ 2 emp > χ 2 tab , it is assumed with 0.95 probability that there is no reason to accept the hypothesis H 0 . It is therefore assumed that a correlation exists between the variables.
In order to determine the strength of the relation between dichotomous variables, the coefficient r c was calculated on the basis of the formula (4) as 0.27.