20 Questions Game

There are many games we remember playing in childhood which were fabulous tools for teaching us how to think and we had no idea they were teaching us – we just thought they were fun to play. A great example is 20 questions, a.k.a. Animal, Vegetable, or Mineral.

How it’s played:

The basic rules: Player One thinks of an item (“the solution”) that the others will attempt to guess. Other players ask a yes / no question. Player One must answer truthfully. Then others players ask another question. They keep asking questions to narrow down the realm of possibilities until they can figure out the solution. If you were to draw out a game, it might look like this. Player One has said they are thinking of a person…

This is a really efficient game, taking only 6 questions to get to the solution. But, they were smart questions… asking gender as the first question cuts the pool of possible solutions in half. Asking whether they’re alive cuts out a huge list of historical figures. This game also assumes that player one and the guessers have a lot of common experiences, where as soon as the guesser  learns they’ve seen the person on YouTube, they know it’s either one of the science videos they watch together or one of the Minecraft / Shopkins / cute cats videos the guesser watches by himself. That makes it much easier for him to narrow it down than it might be for a random stranger who doesn’t know Player One’s YouTube patterns.

Now, when playing with a child for the first many times, it will NOT be this efficient. It could look more like this:

It helps if you play with multiple people… some of whom actually understand the game and can help guide things along. For example, we often play at meal times, where there’s one six-year-old, one or more 20-something people, and two 50-year-olds.

It also helps if you actively teach the child some of the best questions to ask (see strategy below). Then the game might go more like this:

You’ll notice a few things in our example… sometimes we come up with solutions that will entertain the adults, which the child couldn’t have guessed on their own. That’s OK… the child is still getting practice at the game. You’ll also notice we’re not always strict with asking only yes/no questions (We’re OK with a question like “Is it a bird, reptile, or mammal?”) or with only saying “yes” or “no” in our answers (We might say “Actually, it’s an amphibian”). It’s not unusual for us to give a clue in the answer to help guide things along if they’re dragging (“Have I ever seen one of these?” “Yes, in fact,  you can see one right now from where you’re sitting.”)

The “rule” of twenty questions is that you’re supposed to guess the solution in less than 20 questions or you lose. We never keep track of how many questions we’ve gone through. We just play till we’re bored, which is sometimes in five or six questions… then we start giving really obvious hints.

Strategy for Player One

Know your audience!! When you’re choosing a solution, try to think about what will be a little hard for your guessers… 5 – 12 questions to answer, but not something devastatingly difficult. The sweet spot for any puzzle or game is not too easy, not too hard. Too easy is boring, too hard is discouraging. I think with any puzzle, you want the person to have a period when it seems hard, but then they push through and succeed.

Also, make sure the answer is within their realm of knowledge. When I’m playing with my kindergartener, I don’t do historical figures that he doesn’t know, and I ask him not to do obscure Pokemon characters that I don’t know.

Strategy for Guessers

Over time, you can guide your child to understanding effective strategies for the game. In a game where you’re thinking of a person, there are potentially millions of people you could be thinking of… anyone you’ve ever met, read about, seen on TV, etc. If your child starts guessing: Is it Lady Gaga? Is it Barack Obama? Is it my friend from school? Napoleon Bonaparte?…. that could take forever! This is called “linear searching” and rarely makes sense, if you’ve got more than a handful of items to search through.

So, your initial questions are not about trying to guess the exact solution. Instead, you want to ask questions that make the pool of possible solutions smaller. For example, if someone said “I’m thinking of a number between one and 100”, you could say “Is it bigger than 50?” That one question cuts the possible number of answers in half. So would “Is it an odd number?” You could ask “is it a prime number” – if they said yes, that knocks you down to 25 possible answers. (No, I don’t know that there are 25 prime numbers under 100 without looking up a chart of prime numbers… but my husband likely does…)

For experienced players, there are a lot of standard questions you tend to start a game with to quickly narrow the pool. For example, in a game where you were guessing movie titles, you might ask: “kids’ movie or grown-up movie”, “animated or live action”, “was it made in the last 20 years” and so on. Then as you get past all those obvious categories, you have to start getting more specific “Disney or Pixar?” “was main character human” and so on… You could start a game by teaching your child these key questions for that topic. So, for example, if the category was types of toys, some key questions might be: “Is it made of plastic?” “Does it have lots of pieces or is it all in one piece?” “Do parts of the toy move?” “Do I have a toy like this at home?” “What age of kid likes this toy best?” Once you’ve taught the questions, you start the game.

If your child reads, you could even give them a written list of “starter questions” to work from. For example, if the category was animals, this dichotomous key from Mammals: A Compare and Contrast Book by Hall would be a great set of starter questions to help them figure out what category of animal… then they’d ask more specific questions from there.

What are kids learning?

This teaches a way of thinking that provides an approach to problem solving, or to working toward a solution to something by doing “divide and conquer”. Narrowing the range of possibilities till you find a solution. It’s useful not just in the game, but any time we’re trying to guess anything. Where are the Starbucks in Redmond? Well, Starbucks are usually not in small strip malls – they’re usually in bigger shopping centers. Well, what shopping centers are there in Redmond? OK, I’ve thought of several… which ones have Starbucks? Well, Starbucks are often in the same parking lot as a grocery store. So, I would guess these 3 shopping centers with grocery stores all would have one, and I bet the mall would… Solution: Turns out that there are five Starbucks in downtown Redmond… one each at three of those grocery store shopping centers, and two at the mall.

It also teaches us to notice relationships: what things have in common that places them into a category, and what makes them different from each other, which allows us to sort them into two piles to help us find the specific item we’re looking for. This classification / sorting skill is helpful any time we need to clean up a room – the laundry goes here, the books go on the bookshelf – the library books go on the top left corner of the bookshelf… Noticing similarities and differences is also a key skill for scientific thinking.

Game Variants

Guess which picture. This is the most basic level of this kind of guessing game. I’ve played it with toddlers under age 3. Choose a picture (a page from a book, or a doodle you’ve sketched, or whatever) that has multiple items on it, and say “I’ve picked out one of these items as the solution. Can you guess which one?”

A sample game would be: “I’ve picked an animal. Can you guess which one?” “Is it yellow?” “No.” Is it brown?” “Yes.” “Is it the monkey?” “Yes.” You can start with a picture with just 3 or 4 items, then choose pictures with more and more possible solutions as your child gains in skill. You can also do this with physical objects. You can set four toys on the table, and ask them to guess which one you’ve picked.


I’m thinking of….  This is harder than the pictures, because the child has to be able to imagine things they can’t see. It works for age 3 and up. The trick is to have small groups of items, with only a few possible solutions. For example: “I’m thinking about one of the people in our family.” Or “I’m thinking of one of the Paw Patrol characters.” If they don’t understand the strategy of the game, the worst that happens is they have to make 5 or 6 guesses at the most to get the right answer. But you can also teach the first questions to ask… like for Paw Patrol: “Is the character human or a dog?” “Is it a boy dog or a girl dog?” “What color does the dog wear?”

When my son was three, we often played “I’m thinking of a dinosaur”, which got more challenging as he learned the names of more and more dinosaurs. At age 4, a frequent game we played was “I’m thinking of a Star Wars character that starts with the letter L.” When he was being fussy and whiny for no real reason, it was a great way to distract him out of that mood.

Animal Vegetable or Mineral: It’s basically the same game as 20 questions, you just always start with the question animal, vegetable or mineral. Animal means any living (or once living) creature, from tapeworm to dinosaur. Vegetable means any plant. Mineral means things that are not and never have been alive. Each of these categories then has a few obvious starter questions. For example, if the answer was animal, you might first start with figuring out what class of animal. If you learned it was a bug of some sort, you would then try to figure out: arachnid, myriapod, or insect. If the answer was mineral, the first question might be: natural or man-made? Then determining what material it’s made of. Then asking the canonical: Is it bigger than a breadbox?

This variant of the game is obviously really good for teaching taxonomy. But, it sometimes gets a little tricky. For example, if Player One thought of Milk, and then the first question is Animal, Vegetable or Mineral, what’s the answer?? If Player One thought of a wood table… well, it’s made from vegetable, but it’s more of a “mineral” now in that it is not alive now….

Dichotomous Keys: These offer a series of questions. Like a “choose your own adventure”, if you answer yes to #1, it tells you to go to #2. If you answered no to #1, you’d skip ahead to #3. You keep going down the list of questions till you find your answer.

Here is a quick description of a dichotomous key with two examples that elementary age children could follow: http://igbiologyy.blogspot.ca/2012/11/12-using-simple-keys.html. You could use this to teach the idea in a class or home school setting. (Here’s an example for middle or high school age kids: www.biologyjunction.com/dichotomous_keying.htm.)

These science tools can be used as a “game.” You could:

Who Am I? This is a game where you tape a sign on someone’s back, and they have to go around asking people questions till they figure out what’s on their back. You may have done this as an icebreaker or party game at some point, such as where you had to guess which famous person you were. This post describes using it in a fourth grade math class to review math vocabulary.

Group Twenty Questions: The “Guesser” leaves the room. Everyone else agrees on a single object in the room as the solution. Then the guesser comes back in and can ask anyone questions till they get the answer.

Negative Twenty Questions: As described here: There is one “Guesser.” Everyone else chooses an object in the room. I choose the printer, and you choose an empty Coke can, and your buddy Joe chooses their sandwich. The guesser asks me “Is it edible?” I say no, because a printer is not edible. Joe now has to choose a different object that’s not edible. So he chooses his glasses. The guesser asks Joe “is it man-made.” He says yes, and all our objects are, so none of us need to choose a new one. Then he asks you “have you touched it today” and you say yes. Uh-oh, now I have to think of something new, that is not edible, is man-made, and that I’ve touched today, unlike the printer. In theory, at the end of the game, we might all be thinking of the same thing that meets all the criteria.

Wikipedia describes this in a way that gives me a different impression of how the game is played. Nobody chooses an object in advance. They choose a pattern of answers in advance… say no then yes then no…. The guesser asks “is it edible”. The predetermined answer for the first question… whatever it is… was no. So, we all look around and choose an inedible object in the room – there’s a lot to choose from. The guesser asks “is it man-made.” The predetermined answer is yes… and so on.

Negative Twenty Questions was invented by quantum physicist John Wheeler, not really as a game, but more as a thought experiment. This would be a fun variant to try with teens who’d grown bored of the basic game.

Board Game Versions: There are many manufactured games which use these basic rules, but they’ve come up with Solutions for you to use.

  • Guess Who? (Retro Series) Each player has a board with 32 characters flipped up. One draws a character card from a deck, and the other has to guess who it is. “Do they have blue eyes?” If no, then they flip down all the characters with blue eyes, and keep going till they know which character it is. There are other versions of Guess Who? with fewer characters, such as 15 per board, which would be easier for a younger child. I’ve not played this game.
  • HedBanz games involve a player putting a card in a headband so the other people can see it, but they can’t. They then ask the others questions… like in the Disney game, you might ask “am I human?” “Am I a princess?” We played this game when my son was five, and he enjoyed it and could be successful at it IF we were careful about what characters to give him… if we pulled a card from the deck and it was a character he knew well (like Mickey) we’d give it to him… if it was a character he didn’t know (the firefly from Princess and the Frog), we’d draw again.
  • HABA Games Who am I works like HedBanz.
  • Who’s Behind the Door Monster’s University Edition. Each child has pictures of 16 monsters. They ask opponent yes / no questions like: “Is it purple” or “does it have two or more eyes” that allows them to eliminate options till they figure out answer.

Apps: There are a bunch of apps, called things like “Guess Who” and “Who am I” that play off of similar ideas. One we’ve seen played in lines a lot at Disneyland involves one person holding a smartphone up by their forehead so their friends can see the solution, and trying to guess who they are. If you know the name of that one, feel free to add it in the comments.

Miscellaneous Resources

Here’s an interesting lesson plan for teaching middle school to adults about computational search methods using 20 questions.

Have fun playing!


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