The study objective was to substantiate the modes of alternation of physical exercises and rest intervals when teaching series of tasks aimed at motor skills development in boys aged 15 years. Materials and methods. The participants in the study were 40 boys aged 15. The children and their parents were fully informed about all the features of the study and gave their consent to participate in the experiment. To achieve the objective set, the following research methods were used: study and analysis of scientific and methodological literature; pedagogical observation, timing of training tasks; pedagogical experiment, methods of mathematical statistics, methods of mathematical experiment planning. During training, the method of algorithmic instructions was used. Results. The study found that the effectiveness of mastering series of training tasks depends on a mode of alternation of exercises and rest intervals. The results of analysis of variance and regression models show that the optimal mode of performing series of training tasks is within the range of 6-12 exercise repetitions with rest intervals of 60-120 sesonds. In the proposed matrix of factorial design, the selected step of factor variation is sufficient to study the impact of different modes of physical exercises on the effectiveness of teaching children and adolescents. Conclusions. The best options for teaching series of tasks to boys aged 15 during physical education classes are the following: series 1 – 12 repetitions, rest interval of 60–120 s; series 2 – 12 repetitions, rest interval of 120 s; series 3 – 12 repetitions, rest interval of 120 s; series 4 – 12 repetitions, rest interval of 120 s; series 5 – 12 repetitions, rest interval of 60 s; series 6 – 12 repetitions, rest interval of 60 s.

The study objective is to determine the possibility of identifying the state of strength abilities development in boys aged 12-14, using the methodology of multidimensional statistics. Materials and methods. The study involved boys: 12 (n =35), 13 (n = 36), 14 (n = 36) years old. The study used the following methods: analysis and collation of scientific and methodological literature, general scientific methods of theoretical level, such as analogy, analysis, synthesis, abstraction, induction, as well as general scientific methods of empirical level: observation, testing, experiment. The testing program included well-known tests. Results. In identifying the state of motor abilities development in boys aged 12-14, the most important results were obtained in tests: 10 “Squats Test (two legs), quantity of times” (0.519), 9 “Trunk Lift Test, quantity of times” (0.497), 21 “Flamingo Balance Test - single leg balance test” (-0.496), 1 “Pull-Up / Chin Up Test (low crossbar), quantity of times” (0.428), 19 “Hand Tapping Test, sec.” (-0.427), 20 “Seated Forward Bend, cm” (-0.412), 5 “The subject lies in prone position, arms bent at the elbow 90 degrees - hold position in seconds” (0.408). These tests characterize the comprehensive development of motor abilities in boys aged 12-14.  In identifying the state of motor abilities development in boys aged 13-14, the most important results were obtained in tests: 8 “Decline Reverse Crunch on Bench, quantity of times” (-0.989), 11 “Single Leg Squat (SLS) Test - right leg, quantity of times” (0.965), 1 “Pull-Up / Chin Up Test (low crossbar), quantity of times” (0.676), №13 “Single Leg Squat (Pistol) - right leg” (0.682), 17 “Eurofit Sit Up Test (for 30 sec.), quantity of times” (0.454). These tests characterize the development level of  relative and static leg strength, strength endurance of abdominal muscles, and dynamic strength of shoulder muscles. Conclusions. A discriminant analysis made it possible to determine informative indicators for comprehensive control of motor abilities development in boys aged 12-14; to answer the question as to how significantly the states of motor abilities development in boys aged 12, 13 and 14 differ; what motor tests most substantially influence the differentiation of classes; what class the object belongs to based on the values of discriminant variables. To identify the level of motor abilities development in boys aged 12-14 years, it is necessary to focus on the indicators of relative strength and strength endurance; in boys aged 13 and 14 years – on the indicators of strength endurance of abdominal muscles and endurance of leg muscles.

The purpose of the study was to determine the impact of exercises modes on developing a small ball throwing skill in boys aged 8.  Materials and methods. The study participants were 21 boys aged 8, who were randomly divided into three groups of 7 people. The children and their parents were fully informed about all the features of the study and gave their consent to participate in the experiment. The study examined the influence of the number of repetitions on the effectiveness of teaching boys aged 8 throwing a small ball at a target. A pedagogical experiment examined the influence of 6, 12, and 18 repetitions with a 60-second rest interval on the increase in the level of proficiency in exercises of boys aged 8. In the first group, the boys repeated the task 6 times with a rest interval of 60 s, in the second group – 12 times with a rest interval of 60 s, in the third group 18 times with a rest interval of 60 s. When teaching throwing exercises during the class, the study evaluated the level of proficiency by the alternative method (“performed”, “failed”) and calculated the probability of exercise performance (p = n/m, where n is the number of successful attempts, m is the total number of attempts).  In teaching boys aged 8, the method of algorithmic instructions was used. The next exercise started after three successful attempts. Throwing a ball at a vertical target was taught. The study materials were processed by the IBM SPSS 20 statistical analysis software. During discriminant analysis, a prognostic model for group membership was created.  Results. Discriminant analysis made it possible to determine the impact of the number of repetitions on the effectiveness of developing the skills of throwing a small ball at a target; answer the question as to how significantly the modes of repetitions differ by the effectiveness of motor skills development, what class the object belongs to based on the values of discriminant variables. Conclusions. Based on the analysis of group centroids, it was found that in boys aged 8, six repetitions of the exercise (6 sets one time with a rest interval of 60 s) significantly influence the increase in the level of proficiency in exercises during physical education lessons. The results of group classification show that 85.7% of the original grouped observations were classified correctly.

Purpose:The purpose of the study is to determine the possibility of recognizing the state of power abilities development in girls aged 12-14 years based on the methodology of multidimensional statistics. Material:The study involved girls: 12 (n =21), 13 (n = 20), 14 (n = 19) years old. Conclusions:Discriminant analysis allowed to determine informative indicators for cross-control of the development of power abilities in girls aged 12-14 years; answer the question of how significantly the state of development of power abilities in girls of 12, 13 and 14 years is different; which motor tests most significantly affect the differentiation of classes; which class the object belongs to (based on the values of discriminant variables). In order to recognize the level of development of power abilities in girls aged 12-14 years, it is necessary to be guided by the indicators of relative and static strength and strength endurance; at girls of 13 and 14 yearsstrength endurance.

The study purpose was to develop a technology of programming for strength and strength endurance development in middle-school-aged boys in a 4-week physical training cycle. Materials and methods. The study participants were boys of 6th grade (n=35), 7th grade (n=36), 8th grade (n=36). The study materials were processed by the IBM SPSS 23 statistical analysis software. The following parameters were calculated: arithmetic mean (X); standard deviation (s). The probability of difference in statistical indicators was estimated using the Student's t-test. Results. The analysis of the study results demonstrated that after using a combined method of strength development (1-6 classes), the experimental group boys showed a statistically significant improvement in results in the set of tests ( p < 0.05). After using a combined method of strength development, the 6th-8th grade boys had the largest increase in the results of strength and strength endurance of shoulder muscles, strength and strength endurance of abdominal muscles, strength and static strength endurance of leg muscles ( p < 0.05). After using a circuit training method (7-12 classes), the experimental group boys also showed a statistically significant improvement in results in the set of tests ( p < 0.05). The 6th-8th grade boys had the largest increase in the results of dynamic and static strength endurance of shoulder muscles, abdominal and back muscles, leg muscles (p < 0.05). According to the Eurofit motor fitness tests, after using the combined method of strength development (1-6 classes) and the circuit training method (7-12 classes) in a 4-week training cycle, the experimental group boys showed a statistically significant improvement in results in the set of tests (p < 0.05). During the experiment, the 6th-8th grade boys of the control group showed no statistically significant improvement in test results for most parameters (p > 0.05). A comparison between the levels of strength fitness of the control group boys and experimental group boys after the experiment showed that the experimental group boys had statistically significantly better results of strength and strength endurance of shoulder muscles, abdominal and back muscles, leg muscles (p < 0.05). Conclusions. After using the combined method of strength development (1-6 classes) and the circuit training method (7-12 classes) in a 4-week physical training cycle, the middle-school-aged boys showed positive dynamics of strength and strength endurance development of shoulder muscles, abdominal and back muscles, leg muscles. The dynamics of strength and static endurance of the local muscle group is strongly influenced by the combined method of strength development. The circuit training method is effective to develop dynamic and static strength endurance of the local muscle group. For overall development of strength and general endurance, it is effective to use a combination of the combined method of strength development and circuit training method in a 4-week physical training cycle.