The Odd One Out Argument in Ms. Rivera's Word Game
In Ms. Rivera's Grade 2 class, the Wednesday word game uses a card with four words on it. Exactly one word does not belong, and the class must agree on which one. On Tuesday the card read: bus, car, train, banana. The class agreed that banana was the answer, because the other three words name vehicles and banana names a food. Ms. Rivera wrote the rule on the board: 'The three belong to the same group.' On Wednesday the card reads: bat, robin, eagle, penguin. Jada says the answer is bat, because the other three are birds. Marco says the answer is penguin, because the other three can fly. Both children can point to three words that fit their rule, and both rules leave exactly one word out. Ms. Rivera will not say who is right. She taps Tuesday's card and says: 'Look at what kind of rule we used yesterday, then check the three words that are left.' The class has four minutes before music.
1. Which word should the class choose, bat or penguin? Name the rule you are using, and explain why the other answer is true but still not the best answer for this game.
Read the worked answer
Choose bat.
The rule must be the same kind of rule that made banana the answer on Tuesday: a 'what kind of thing is it' rule, not a 'what can it do' rule. Robin, eagle and penguin are all birds, so the leftover bat is the one that is not the same kind of thing. Bat is a mammal.
Marco's fact is real. A penguin cannot fly, and the other three can, so his rule also leaves exactly one word out. That is why the card is hard. The tie-breaker is not which answer feels more different; it is which rule matches the kind of rule the game has been using. Category rules group by what something is. Ability rules group by what something does. This game has used a category rule, so bat is the answer.
2. A classmate says, 'If two answers can both be explained, the game is broken.' Explain why the game still has an answer, and describe the check a student should run before choosing.
Read the worked answer
The game is not broken. It is asking which rule fits the game, not which rule is merely possible.
Run a three-step check:
- Find the rule that groups the other three words.
- Name the type of that rule: same kind of thing, same action, same sound, same place.
- Compare it with the rule type on the example card. If the example used a kind-of-thing rule and your candidate uses a can-do rule, your candidate is the weaker answer even though the fact is true.
Then run a safety check: which rule is supported by more than one shared feature? Robin, eagle and penguin are birds, have feathers, and lay eggs. Robin and eagle also fly, but bat shares only the flying feature with them. The answer backed by more shared features is the stronger one.
3. Write a four-word card where two different rules give two different answers, and label both rules. Then say which answer your card makes stronger, and why.
Read the worked answer
Card: cat, dog, fish, chair.
- Rule 1, 'not a living thing,' makes chair the odd word.
- Rule 2, 'has legs,' makes fish the odd word, because cat, dog and chair all have legs.
The two answers are different, which is what the task asks for. Rule 1 is the stronger answer, because the three leftover words share more than one feature: cat, dog and fish are living things, are animals, and move on their own. Under rule 2 the leftovers are tied only by having legs, and one of them is not even alive, so that group is a mixed bag.
A card like this is exactly what makes the Wednesday game interesting, and it shows why Ms. Rivera checks the three leftover words, not just the odd one.