Practise the thinking. Keep the judgement.
OC thinking skills: test a conclusion against every condition
Use a small ordering problem to distinguish a necessary conclusion from one possible arrangement.
Record only the relationships you are given
In an ordering problem, write each condition as a simple before-and-after relationship. Do not place an item first or last just because it appears first in the sentence.
Then identify what the question asks: a possible arrangement or a statement that must hold. One valid arrangement is enough to show possibility, but not enough to prove necessity.
Keep two valid orders visible
Original example: A finishes before C, and B finishes before C. Both A-B-C and B-A-C fit. C must be last among these three, but the order of A and B remains unknown.
If an option says A must finish first, the second arrangement is a counterexample. It respects the conditions while making that option false. You do not need to invent another condition to decide between A and B.
Add a condition and revisit the conclusion
Now add “A finishes before B”. Only A-B-C remains among the two arrangements. The new condition changes what can be concluded, so keep track of which conclusions use which information.
This habit is useful when a question introduces an extra statement. Re-read all the conditions instead of carrying forward an assumption from the earlier version.
Explain the reason for rejecting an option
For a “must” question, try to construct a valid counterexample to a doubtful answer. For a “could” question, construct one valid example. Check every stated condition in that example.
At review time, name any assumption you added. A note such as “I assumed A was first because it was mentioned first” gives you a precise mistake to avoid in the next task.
Try it yourself
M is taller than N. P is taller than N. Must M be taller than P?
Show the answer and explanation
No.
Both M and P can be taller than N in either order. Their relationship is not fixed by the conditions.