## 3 Research Design
### Overview of the Learning Loops for the HECOF NTUA Pilot  
The following learning loops were designed for NTUA: guided mastery, reinforcement practice, practice through VR and think-pair-share. Table 2 presents a summary of the learning loops in terms of goals, rationale, benefits to students, adaptivity, and format. Guided mastery includes a concept-level mastery strategy and progress in map-order through concepts in the topic towards mastery coverage. The NTUA guided mastery learning loop is a structured learning experience that ensures students achieve concept-level mastery by progressing through topics in a curriculum map sequence. The learning loop implements a balanced adaptive learning approach based on all available content towards mastery of the lesson and knowledge acquisition. A strong student will most  
Figure 2: High-level illustration of the Learning Activity Matrix for the NTUA pilot. likely go through instructional tasks and exercises (quizzes) and, as soon as there are signs of a low success rate (lower probability to pass), alternative paths with remedial instructional content are given to the students. The rationale for this loop is rooted in the mastery learning theory [60; 61; 62] and in previous research in adaptive and intelligent tutoring [58; 63; 64; 65]. Figure 3 presents the schematic adaptation of the guided mastery loop that was configured using the AI Engine. The learning loop takes students through instructional content and exercises (quizzes) through easy, medium, and hard quizzes (exercises). The students will go progressively through easy, medium, and hard levels of knowledge acquisition. At each level, if the students show a lower probability to pass, remedial instructional content is presented, followed by an additional exercise (quiz). Additional path change is available if the students struggle again. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline  
The reinforcement revision loop includes an interleaved reinforcement strategy and performs a course-level spaced revision of recently acquired concepts to reinforce and consolidate previous learning. The loop uses mainly assessment items and is aimed at giving course-level spaced repetition of acquired concepts following a memory bucket approach after students have mastered the concepts. Furthermore, a summary of each concept is provided for the most forgotten concept. The rationale for this loop is rooted in previous research of model forgetting and spaced repetition [66; 67; 68; 69; 70; 71]. Figure 4 presents the schematic adaptation of the loop that was configured. Students will start by selecting their goal (i.e., number of questions to revise) and will answer questions from the already mastered concepts. As mentioned, the concepts will be selected following the space repetition approach with the most overdue for revision being priorities first. In addition, a summary of the most forgotten concept will be presented to students. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
\begin{tabular}{c}  
The practice (VR) loop includes a VR experience to enable the practice of experiments. This loop enables students to gain practical experience, enhance comprehension about practical aspects, and makes the experiments accessible to students. Practice (VR) will include VR content objects. The rationale of this loop is rooted in virtual labs and VR-based education [72; 73; 74; 75; 76; 77]. Figure 5 presents the schematic adaptation of the practice VR loop. Inside the VR learning loop, students will proceed through the following: (1) apparatus investigation--with the role to allow students to accommodate VR and the apparatus used in VR; (2) guided experiment--with the role to allow students to perform an experiment in a guided mode, where, step by step, the experiment is explained to them; and (3) challenge experiment--with the role to allow students to perform an experiment on their own.