Reasoning · Grade 6-1 Deductive Logic (2)
Problem
Number the seats and fix which way is left.
Describing where things are with words like beside, above and to the left is Kindergarten position language; the only care needed is that the people face the middle, so their left is not the reader's left.
K.G.A.1Visualize Spatial RelationshipsThe first clue leaves D two seats.
Starting with the most restrictive clue is what keeps the work short: one sentence has already cut D's five choices down to two.
K.G.A.1Eliminate PossibilitiesThe first clue leaves D only two possible seats, which cuts the whole search to two branches.
Every seat that the clue makes impossible is crossed out at once, so only the survivors need following up.
Each person takes exactly one seat and each seat holds exactly one person, so fixing D also takes that seat from everyone else.
The second clue attaches E to D.
A clue that ties two people together is worth more than a clue about one person, because it places both of them at once.
K.G.A.1Eliminate PossibilitiesThe third clue kills one branch.
Once three people are placed the last two have no freedom at all, so you can test a branch just by looking at which pair of seats is left over.
K.G.A.1Eliminate PossibilitiesThe fourth clue settles the last two seats.
A clue phrased as 'is not' still decides things when only two possibilities are left: ruling one out is the same as choosing the other.
4.G.A.1Eliminate PossibilitiesThe order is A, B, D, E, C.
Reading every clue back against the finished drawing catches a misread left-or-right immediately, because the wrong reading would fail clue 2 or clue 4 straight away.
4.G.A.1Draw A DiagramOf 24 seatings only one survives.
Counting the whole search space first and then watching the clues close every branch but one is what turns 'I found an answer that fits' into 'this is the answer'.
3.OA.A.1Make A Systematic ListSit yourself in one of the chairs facing the table first — then 'to my left' becomes a direction you can point at in the picture.