I. Background3D-Virtual Learning Environments (3D-VLEs) are the representation of 3D space inside the computer memory which enables students to navigate freely inside the virtual world and process different objects in real time [1,2]. Adaptive 3D-Virtual Learning Environments (3D-VLEs) change its contents at run time according to the learning needs of individual student [3,4]. These environments have many advantages. It display personalized learning contents to each student, reduces the probability of astray navigation inside the virtual environment and makes the distinction between education and entertainment which improve the learning process of students [5][6][7] . In literature a lot of work has been done which support the use of cognitive aids (Audio, Visual and textual etc) in virtual learning environments. For example, Nguyen et al. [8] used lighting source , arrows, and a compass as navigational guiding aids which help trainees to find the target. Gavish et al. [9] presented a 3D virtual puzzle in which verbal instructions plus mouse pointing are used to find the target location on learner screen. Similarly, Ali et al. [3] developed Multimodal Virtual laboratory (MMVL in which students were provided both audio and visual support during experiments which improved their efficiency.The use of these aids reduce mental load on learner as it provide a specific and easy to follow instructions mechanism to perform the task [9]. However, these aids can act as shortcuts and prevents the trainees from active exploration which is necessary to perform the task independently in non-supervised environment [10][11][12]. Therefore, a mechanism is needed to use these aids while minimizing their negative effects. Jorge, R. et al.[13] recommended the control use of cognitive aids and proved that it will not affect the performance of the trainee in the real environment. Similarly, Rehman et al. [14], suggested the use of semantic aids with direct aids to maximize active exploration in virtual environments. In this paper we used adaptive repetition as a strategy to explore the 3D-Virtual Learning environments. The proposed approach enables the trainee to get the benefits of cognitive support while at the same time he is actively involved to explore the environment. We also tried to find the number of adaptive repetition required by the weak, average and good students to actively explore the virtual environment and perform the task successfully in non-supervised environment". The remaining paper is organized as below.In section II we discussed the proposed approach followed by implementation in section III. In section IV we presented experimentations. Discussion is given in section V followed by conclusion in section VII.
II. The Proposed Approach
The Learning Decision Function (LDF)With the help of Learning Decision Function (LDF), we can measure the learning skill of students in 3D-VLEs and declare it as weak, average and good learners [15]. The LDF takes time, no of errors and test scores of a student as inputs, calculate ...