Item statistics, a plus-ten proposal, and a parent on the board of trustees
You are the Grade 9 biology teacher and assessment coordinator at a school in Aktobe. Seventy-eight students sat a 30-item term summative assessment, one point per item, with a school pass mark of 50%. Results: mean 54%, and 31 students below 40%. Your item analysis gives: item 7, difficulty 0.62, discrimination 0.41; item 14, difficulty 0.83, discrimination -0.12; item 22, difficulty 0.12, discrimination 0.05; item 26, difficulty 0.55, discrimination 0.38, but its wording refers to excretion in plants, which was not in the taught units. The vice-principal, whose son scored 42%, proposes adding 10 points to everyone 'so the class average looks normal for the inspection'. A parent who sits on the school's board of trustees has emailed demanding to see her daughter's scored script and asking why only three students scored above 90%. Two students have asked to retake.
1. Interpret the four item statistics and state what you would do with items 14, 22 and 26.
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Read the statistics correctly first. Difficulty is the proportion answering correctly. Discrimination is the difference in performance between the strongest and weakest students; near zero means the item does not separate them, and negative means the strongest did worse than the weakest - a signal of a defect, not of a hard topic.
- Item 7 (0.62, 0.41): a well-behaved item. Keep it; it is also a model for rewriting others.
- Item 14 (0.83, -0.12): easy, yet the strongest students got it wrong. That pattern is almost always a miskey or a second defensible answer. Check the distractor distribution: if the top quartile clusters on one option while the key names another, the key is wrong. If so, re-key and rescore all 78 scripts, and say so in writing.
- Item 22 (0.12, 0.05): almost nobody, and no separation. Either the objective was not taught, or the item is unreadable or multi-step beyond the blueprint. Check the scheme of work. If it was taught, discard the item from scoring and reteach the objective; if it was not taught, it should never have been on the paper.
- Item 26 (0.55, 0.38): statistically healthy but out of scope. A test can only score what was taught; scoring it punishes students for the school's error. Remove it from the total.
Then, and only then, recompute. After re-keying 14 and removing 22 and 26, the maximum is 28 and the percentages change. Decide the pass rate on the corrected data before anyone discusses the average.
2. How do you respond to the vice-principal's proposal to add 10 points to everyone?
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Refuse the adjustment, offer alternatives, and put the reasoning in writing.
- Why it is wrong in principle. The marks are criterion-referenced: they report whether each student met specific objectives. Adding a constant does not change what anyone can do, destroys comparability with the other Grade 9 classes and with next term, and misreports a student's competence to parents and to the next school. It is also the change most likely to be spotted in an inspection, because the raw scripts and the reported scores will not match.
- Note the conflict of interest, neutrally. The proposal comes from the parent of a student at 42%. Do not say this in the meeting; record the request, your response and the reason in a short memo to the deputy for academic affairs, and ask for the decision to be minuted. This protects the vice-principal as much as you.
- Offer legitimate routes to a better number. Correct item 14 and rescore; remove items 22 and 26; publish the corrected distribution; reteach the weak objectives and re-assess those objectives with new items after two weeks; report the intervention and its result alongside the original data.
What to say. 'The average can be improved by fixing the test and then teaching to the gaps. It cannot be improved by changing the arithmetic, and if it were, the next test would show the same gap with no explanation.' Honest data plus a documented action plan is a stronger inspection story than an average nobody can trace.
3. How do you handle the trustee's demand to see the script and the two retake requests?
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The script request: follow policy, protect other students. Check the school's assessment policy - most allow a parent to view their own child's marked script under supervision, with no copies and no removal. Offer a scheduled 20-minute review with the teacher present, and use it to walk through the criteria. Refuse, politely and in writing, anything that exposes other students' marks or the class list. Answer the 'why only three above 90%' question with the distribution and the item analysis, not with names: the paper was long and two items were unfair, which compressed the top end - and that is now being corrected.
The retakes: separate two different things.
- Appeal for a marking or key error: not a retake at all, a re-mark. Handle it through the correction of item 14 and the removal of items 22 and 26; anyone who crosses the pass mark as a result is passed, and that is the school's error being fixed.
- Second attempt to improve a valid mark: a different question. Check policy. If re-assessment is permitted, it should use new items on the same objectives and be offered on the same terms to everyone in the affected group, not only to those who ask. Offering it only to the two who asked is inequitable and indefensible if challenged.
Document everything. The parent's email, your reply, the item review, the rescoring, the re-assessment decision and its criteria. In assessment disputes, the teacher with a dated paper trail is the one whose professional judgement survives.