HCD.4:5.5 - A Local Model for Selecting the Unit of Work
Coordinator-N24 is fictional. The following tasks, observations and resources are stipulated teaching data, not a measured learning study. N24 must estimate active processing work from request records. In this case each distinct request needs 18 minutes, and each duplicate message adds no further processing. These simplifying assumptions are supplied domain facts; real coordination, queueing and variable request effort require their own model.
The target is to choose the unit appropriate to the requested result, calculate the active effort and state its boundary. In two initial tasks, N24 calculates correctly when given the number of distinct requests. With 80 message records including 20 duplicates, N24 initially uses 80 and returns 24 hours. After a teacher asks which records concern the same request, N24 groups them into 60 requests, returns 18 hours and explains the difference. The first response and the helped correction are separate evidence.
The practitioner constructs this small model:
| Contribution | Candidate qualitative descriptions | Current position and intended change |
|---|---|---|
| selecting the unit | follows the salient record label; uses the work request when grouping is prompted; independently chooses and checks the unit against the receiving question | The first two are observed. Independent selection is the target, with uncertainty about cues and context. |
| carrying out the calculation | needs the unit and operation supplied; applies 18 minutes per distinct request with ordinary calculator access | The second is supported when the unit is given. Preserve it while changing selection. |
| coordinating the result | reports a number without its scope; relates the estimate to active effort while keeping response time and queue clearance separate | Include that scope distinction in whole-task practice; do not infer it from arithmetic alone. |
Model M0 tentatively orders independent selection by context familiarity: success in new service contexts is expected to come with reliable selection in familiar ticket formats. This cumulative proficiency hypothesis would favor familiar-format practice before moving to new contexts. Its basis is a plausible teaching assumption, not an established prerequisite. M0 also predicts that an explanation of the duplicate/request relation will help selection; the earlier helped explanation has not yet tested independent use. HCD.6:5.6 constructs two routes that could address that difference.
The two candidate orderings lead to different observations: noticing duplicate signs is not yet recognizing the unit conflict; recognizing that conflict is not choosing the relevant operation; supported grouping is not independent selection. Explanation, calculation, selection and qualification of the whole result remain distinguishable. Whether learning them also supports later adaptation or repair needs separate observations. Teaching another person is outside this target, not an automatic next stage. The observation and revision of M0 are developed in HCD.6:5.6.