10.3Math Explorer · Logic I
Lesson progress0 of 10 missions
Chapter 10 · Logical Reasoning I

Rank and Match with a Logic Table

Lesson 10.3 · 用逻辑表进行排名与配对

Turn spoken predictions into a one-to-one table, test a branch, use contradictions, and audit every clue before accepting a ranking.

One person per rank. One rank per person.

Grade 5Self-containedEverything needed is on this page.Objective grading
Mission 1

Build the one-to-one rule

In a no-tie ranking, every person occupies exactly one rank, and every rank belongs to exactly one person.

Not complete
1rank for each person
1person in each rank
0ties unless stated

Try a small logic table

Click a cell to cycle through:

? undecided× impossible confirmed

When you confirm one match, the table marks other cells in that row and column as impossible. If you confirm incompatible matches, it reports a contradiction; change or clear the conflicting assumptions.

No match is confirmed yet.

Check the rule

Mission 2

Translate predictions into a table

Four observers predict the ranks of five Go players A, B, C, D, and E. There are no ties. Each observer has exactly one correct prediction and one incorrect prediction.

Not complete
ObserverPrediction 1Prediction 2Truth quota
JiaE3rdA4th1 true · 1 false
YiA3rdB1st1 true · 1 false
BingB4thE2nd1 true · 1 false
DingD1stC3rd1 true · 1 false
Two different tables: the prediction table records what people said. The logic table records which person can occupy each rank. Do not mix the observer names with the competitor names.
Prediction original1st2nd3rd4th5th
JiaEA
YiBA
BingEB
DingDC

Read the table precisely

Mission 3

Test the branch “E is 3rd”

A branch can look reasonable at first. Follow every consequence until it either survives or creates a contradiction.

Not complete

Rank board

Reveal the assumption first.

Assume: Jia’s first claim is true, so E is 3rd.
Use no ties: A cannot also be 3rd, so Yi’s “A is 3rd” is false.
Use Yi’s quota: Yi’s other claim must be true, so B is 1st.
Use Ding’s quota: D cannot be 1st, so C must be 3rd.
Contradiction: E and C would both occupy 3rd place.

Explain why the branch fails

Mission 4

Reject the branch and propagate forced matches

Once “E is 3rd” is rejected, Jia’s other claim becomes true. One forced match creates the next.

Not complete

Ranking as it becomes forced

Start by rejecting E in 3rd place.

Conclusion after rejecting the branch: E is not 3rd.
Jia: A must be 4th.
Yi: A is not 3rd, so B must be 1st.
Bing: B is not 4th, so E must be 2nd.
Ding: D is not 1st, so C must be 3rd.
Remaining place: D must be 5th.

Record the forced matches

Mission 5

Audit the complete ranking

A candidate ranking is not finished until it passes the one-to-one rule and every observer’s exact truth quota.

Not complete

Enter one player in each rank

Enter all five ranks to begin the audit.
Mission 6

Practice with four competitors

The same table method works with a different number of people. Every speaker again has one correct and one incorrect claim.

Not complete

Complete contest statement

Xiao Zhang: “Xiao Li is 1st; I am 3rd.”

Xiao Wang: “I am 1st; Xiao Zhao is 4th.”

Xiao Li: “Xiao Zhao is 2nd; I am 3rd.”

There are no ties, and each speaker has exactly one correct claim.

Enter all four ranks to begin.

Submit the ranking

Mission 7

Find the one wrong prediction—without inventing a full ranking

Sometimes the clues determine only what the question asks. Here, exactly one player’s prediction is wrong, but the middle two ranks are not uniquely fixed.

Not complete

Predictions

Player A“I definitely will not be last.”
Player B“I cannot be first, and I will not be last.”
Player C“I will definitely be first.”
Player D“Then I will be last.”

There are no ties. Exactly one complete prediction is wrong. B’s two clauses count together as one prediction: it is true only if B is neither first nor last, and false if either clause fails.

ABCD
Do not overclaim: if two complete rankings satisfy every clue, the full ranking is not determined. Report only the fact the problem actually proves.
Mission 8

Cover every rank

This five-person, no-tie ranking uses a different rule: every rank from first to fifth was guessed correctly by at least one student. It does not say that every student got exactly one claim right.

Not complete
StudentPrediction 1Prediction 2
ZhaoQian is 3rdSun is 5th
QianWang is 4thLi is 5th
SunZhao is 1stWang is 4th
LiSun is 1stQian is 2nd
WangZhao is 2ndLi is 4th

Who was predicted for each rank?

Rank 3: only Qian was predicted for 3rd, so Qian must be 3rd.
Rank 2: Qian or Zhao was predicted; Qian is already 3rd, so Zhao is 2nd.
Rank 1: Zhao or Sun was predicted; Zhao is already 2nd, so Sun is 1st.
Rank 5: Sun or Li was predicted; Sun is already 1st, so Li is 5th.
Rank 4: Wang is the only remaining person, so Wang is 4th.

Enter the final order

Mission 9

Fresh workshop

Try all six fresh checks. Use a hint after your first attempt.

Not complete

Ari, Bea, and Cal finish a race with no ties. Ari is not last. Bea finishes before Ari.

One hint

Ari cannot be last, and Bea must have a place before Ari.

Worked reasoning — open after trying

Ari cannot be first because Bea must be earlier. Ari is second, Bea first, Cal third. Check both clues and all three ranks.

Mission 10

Fresh exit challenge

Complete Missions 2 and 4, this workshop, and all five exit checks to earn your certificate. Reflection and extra exploration are optional.

Not complete

Dee, Eli, and Flo finish with no ties. Flo is before Dee and Eli is before Dee. No clue compares Flo and Eli.

One hint

Both other racers must precede Dee. Swap their order to test uniqueness.

Worked reasoning — open after trying

Flo/Eli/Dee and Eli/Flo/Dee both work. Dee is uniquely third; neither earlier rank is fixed.

1↔1

Lesson checkpoints completed

Logic-Table Ranking Architect

You completed the checkpoints on one-to-one matching, contradictions and checking every clue. Revisit any steps for which you needed solution help.

Teaching notes

Every original puzzle used here is restated in English.The interactive logic tables, branch visualizations, audits, and assessments are added instructional scaffolds.