1. Preparing exercises with a device to develop the motor behavior for the accuracy of the skill of crushing the volleyball from a sitting position.

2. To identify the effect of exercises by using a device to develop the motor behavior of the skill of crushing hitting the volleyball from a sitting position.

As for the research hypothesis, they were

1. There are statistically significant differences between the results of the pre and post tests of the experimental and control groups in the motor behavior of the accuracy of the skill of crushing the volleyball from the sitting position.

2. There are statistically significant differences between the results of the post-tests of the experimental and control groups, in favor of the experimental group in the motor behavior of the accuracy of the skill of crushing hitting the volleyball from the sitting position.

The second chapter included a detail in the research methodology and field procedures, as the researcher used the experimental method in the style of the experimental and control groups, with two pre and post tests, due to its suitability to the nature of the problem. Choosing the research sample by the intentional method, which is (12) players, where (2) of the players were excluded as free players, the rest (16) players, and (4) players were excluded from the exploratory experiment on whom the exploratory experiments were conducted for the tests and exercises set, as the percentage of the research community and sample reached (66%) After that, the sample was divided into two experimental and control groups, in a random manner by drawing lots. The number of each group is (6) players. As for the third chapter, the extracted statistical results were presented in charts, with the analysis of those results and their discussion according to the theoretical knowledge foundations based on the references. Scientific, and in the light of the experiment carried out by the researcher and the results achieved through tests and statistical methods, he reached the following conclusions:

1. The correct scientific method of the exercises used with the device in the gradation from easy to difficult helped the experimental group to reach the desired goal, which is to develop the motor behavior of the accuracy of the crushing skill of the volleyball players from a sitting position.

2. The use of multiple training and educational methods according to modern devices helps players develop their abilities, as well as controlling the use of means and devices to increase the degree of difficulty during training (which is therefore somewhat similar to the conditions and atmosphere of the game), which adapts the player to those stimuli and increases experience and then Increases his potential for proper motor behavior in matches.

3. The proposed exercises prepared by the researcher using the device helped in developing the motor behavior of the crushing skill of the experimental group more than the exercises used for the control group.

As for the recommendations, they were

1. It is possible to rely on the tests used in the research to identify the performance level of the motor behavior of the crushing skill.

2. The researcher recommends providing auxiliary devices and tools in sports halls for the purpose of developing basic and technical skills, and suitable for volleyball players from a sitting position.

3. Instructing the trainers to give importance in their training to developing the motor behavior of the various skills, especially the crushing skill.