Staff chooses one file after feedback and a delay. Learners use the assigned source/task only. Capture this first response before its matching later page. All numbers and descriptions are original conceptual models, not actual investigation results.
F2 first
Source: Cube G has edge 2 mm; H has edge 4 mm. Area = 6a²; volume = a³; face-to-centre distance = a/2; SA/V = area/volume. Each has a supplied layer 1 mm deep at 4 min. Central edge = max(a − 2d, 0); fraction penetrated = 1 − (central edge/a)³; For this supplied interval, the layer starts at depth d_start = 0 mm when t_start = 0 min. Average front speed = Δdepth/Δtime = (d_end − d_start)/(t_end − t_start). This is the model's interval average, not a constant future speed, intrinsic diffusion coefficient or molecular flux. In a separate supplied endpoint file G has 80, 90, 100 s and H 90, 100, 110 s, with independent model samples. Material, solution and endpoint rule match; temperature, stirring and measurement resolution are unknown. Imposed layers and endpoint times are separate model descriptions.
Task: Calculate both areas, volumes, ratios with units, centre distances, penetrated fractions and average front speed. Distinguish total surface from ratio and explain why fraction is not speed, including the zero-core/full-penetration case. Calculate means/ranges, compare the overlapping lists, name missing conditions or measurement information, and suggest an improvement. State whether an actual learner investigation occurred. Preserve first work before the later page.