This subunit consists of 5 activities. The order and flow of activities are presented below. The activities are created in this way that they offer a complete learning cycle.
| File ID | Activity Name | Inquiry Type | E-emphasis |
| XVi.2.1 | X the unknown | Guided discovery | 1. Engagement 2. Exploration 3. Explanation 4. Elaboration/ Evaluation |
| XVi.2.2 | Interaction with matter | Bounded inquiry Guided inquiry |
1. Engagement 2. Exploration 3. Explanation 4. Elaboration/ Evaluation |
| XVi.2.3 | X-ray medical machine | Guided discovery | 1. Engagement/Exploration 2. Explanation 3. Elaboration/ Evaluation |
| XVi.2.4 | CT scans | Guided inquiry | 1. Engagement 2. Exploration 3. Explanation 4. Elaboration 5. Evaluation |
| XVi.2.5 | Are X-rays bad for you? | Open inquiry | Elaboration/Evaluation |