When It Pays to Say "I Don't Know"

In response to our recent podcast called “Why Is ‘I Don’t Know’ So Hard to Say?,” a reader named Timothy McCollough writes in with a most interesting story. He teaches at a private international school in Santo Domingo, Dominican Republic. His courses include two sections of AP microeconomics, sociology, and “regular economics.” Because it’s a private school, he adds, “we have freer reign to set up classroom incentives and engage students as we see fit.” For instance:

In my classroom, students lose 1/4 point for wrong answers on quizzes. But for writing “I don’t know,” they get 1/4 point. (A correct answer is 1 point). The rationale is that if someone is in a medical emergency, and someone asks me what should be done, the answer “I don’t know” is much preferable to a guess. “I don’t know” leads the questioner to ask someone who hopefully is knowledgeable.

Part of why “I don’t know is so hard to say” stems from an education system based on attempting every single question, whether you know the answer or not.

P.S.: End-of-year student survey showed students strongly supported the +1/4 point IDK and -1/4 point wrong-answer system. 

 I have to say, I very much like to see this kind of creativity in a teacher, any teacher, at any level. 


Bobby G

How does that system work on a test with "partial-credit-eligible" questions?

Econ and Sociology, at least at the upper level of education, are almost entirely "It depends" answers. I'd imagine writing IDK becomes less lucrative when you know at least one portion of how to answer a question. I'm curious what his response to the medical emergency analogy would be then.

"Quick, what do I do after impaling myself on this fence?"
-"Well, I know step one is to remove the thing that is impaling you, but I don't know anything after that."

Partial credit, while valuable in the classroom (in my opinion) wouldn't be too helpful in that medical situation above :).


Actually, the worst thing to do when significantly impaled is to remove the object. The object is helping to prevent bleeding by applying pressure to the wound and removing it could (and usually does) cause a drop in blood pressure which could lead to shock and a host of other issues. Instead care should be taken to clean the area around the wound and stabilize the object. If you're caught on a non-mobile object (like a fence post stuck in the ground) you should try to cut the object in a manageable piece, or if it can't be done safety, call 911 and have trained professionals handle the situation.

In the case, saying out right that "I don't know" but I should get help from someone who does is still the preferred response. Today's society with the internet, calculators, and cell phones is not about knowing information, but knowing how to access information


This is a good idea except for the fact that most teachers are forced to "teach to the test", which incentivizes guessing.


The model by Mr. McCollough is pretty interesting but I cannot see it working in American public schools.

I know of a math teacher that allows students to re-take tests an unlimited number of times. His thought is that people have unlimited opportunities to apply for a Driver's License and other important facets of adult life. He always changes the numbers on each test, of course.

With SATs, ACTs and various other standardized tests in the United States, students are encouraged to attempt some form of a guess rather than skipping the question altogether.

I hope Mr. McCollough sees positive results in his classroom and I also hope that he adapts to his students over time. One thing I am learning as a young teacher is to employ strategies and incentives that are specially tailored to individual classrooms rather than a "one size fits all" approach.


Guessing doesn't help on the SAT. You lose points for incorrect answers. If you can't eliminate any answer options, it's better to leave it blank.

Matt M

I think I understand the reasoning but to me it feels too much like a reward for quiting. Do the benefits for knowing when to say IDK outweigh the confidence one can get from attempting and succeeding at something risky? I think no.


I'm sorry but this is really stupid. You're supposed to learn. If you didn't learn, that's OK, that does happen but there is no way that you should be rewarded with a +1/4 point for that! You mean to tell me that if you studied and you attempted a question and got it wrong you get a -1/4 point but if you just sat there and didn't even bother trying to learn something and then put IDK on the test then you get a +1/4 point?

By the way, of course students strongly support it! It gives them points (OK, fractions of points) for zero effort. I bet if you gave them 50 points for signing their name they'd support that too.


The idea is fine except completely irrelevant or idiotic answers should be given -25% credit. In other words it is possible to earn an overall negative test score for wasting the teacher's time with drivel. This is more inline with how the real world works. If I mail something to the wrong address I get to pay the postage again for mailing it a second time to the correct address. If I don't want to pay twice then I better get it correct the first time.


I'm a 8-12 grade teacher (Latin, public school) and I feel like this would be a terrible system in my classroom. Many of my students tend to give up too easily. If the answer doesn't come to them in an instant, they leave it blank and turn the paper in half-completed. Each time I give them the paper back (immediately) and tell them to think about it some more. They always complete more, and usually get about half or so right. When we go over the quiz (immediately afterward) there are always one or two students who shout out, "Oh, I thought that was the answer, but I left it blank because I thought it was wrong." They're so afraid of getting the question wrong that they don't try to get it right.

I feel like Mr. McCullough's system makes it too easy for kids to cop out. Perhaps he gets a different caliber of student in his private school, but I think many of my students would take that option if it were available, even though they likely could have gotten more points by really making an attempt. The reasoning seems odd also - I'm not sure my students would confuse a Latin quiz, which they do know something about, with a medical emergency.

My solution is what Matt mentioned above - I let my students retake quizzes. My reasoning is that I just want them to learn the material, and if it takes them two, or three, tries then at least they learned it in the end. It works for me and my students.



You have the opposite problem Mr. McCullough has; instead of student's blindly guessing, your students are refusing to make an educated guess. I'm curious on your student's rationale for leaving things blank. I presume that your exams award zero points for wrong answers and zero points for blank answers. What benefit is there for a blank answer if they have a possible correct answer in mind? A chance to get some points sounds better than a guarantee to get none.

I'm also not a fan of getting to retake quizzes. I'm no educator, but to me it encourages students not to bother trying the first time, since there is always another chance.


Hey, I'm on your side - that's why I always give the papers back and make them put the effort in. I think that somewhere along the line they have become so fearful about getting something "wrong" that they would rather not try (and thus have no chance of getting something wrong, in their minds at least) than attempt something with the possibility of getting it wrong (despite the chance of getting it right, too).

Regarding the retakes, I thought the same initially. It turns out that there is a subset of students who will study hard and do well the first time, always. There is also a group of students who won't put any effort in no matter the incentives. But there is a subset who mean well but sometimes mess up -- the athletes who often lack the time to study, those who did try to study but mixed up the ideas in their mind, or the kids who just plain forgot. These are the kids who benefit from my retake policy. Like I said, I want them to know the material, and this encourages them to go back and learn it. This gives them an incentive to do so, plus it shows them that I actually want them to learn (it's kind of surprising how they think all teachers are out to get them).



Awful. Schools should be a risk-free environment. You learn best when you make mistakes.


Tell that to your flying instructor :-)

The real world is not a risk-free environment, and one of the things that needs to be learned is how to judge the potential consequences of making mistakes.

I've always thought that learning by trial & error is in fact one of the least effective means of learning, used only by those too lazy to RTFM.


In my classroom I hate it when students leave blank answers. I would rather have a student guess and attempt to answer. They often attain at least partial credit for knowing some of the material. Kids often give up way too quickly and I want to challenge them to think about a problem for a while.


As a university TA, I hate it when students fill in answers that are completely wrong and hope that knowing something--anything--is good enough - a waste of time trying to fish through the mud. Of course, beyond high school, test time is too late for learning so valuing "I don't know" is more worthwhile.


I believe this is a great approach for collegiate education, but not necessarily in grade school. I could see it working in an advanced gifted/talented class...but not as a role in all classes. The question of applying this broadly aside, the point of the article is that being able to say "I don't know" instead of trying to BS your way through a response is a life skill that we should do more to reach our kids. And our adults. It is one part humility and one part intellectual curiosity, both of which are seriously lacking today.

Katie F

I can understand taking away 1/4 for a wrong answer to discourage guessing, but giving 1/4 for saying "I don't know"? That's just silly. Why not just give 0 points if they leave the answer blank (which is essentially "I don't know")? That way, you're encouraged not to guess randomly, yet you're also not rewarded for not knowing the answer.

Plus if I were in school, it would infuriate me that someone like me, who worked really hard, could be getting 1/4 points off for making genuine attempts at answering the question, yet getting them wrong, while someone who blew off studying and showed up to class having done nothing could write "I don't know" on practically everything and still possibly get the same or even a better grade than me. I am making an honest attempt at learning material and could just be struggling on that particular test. The other guy is just being lazy. Do I deserve to be put on the same level as someone who did the bare minimum?

Also, medical emergencies are not the same as tests in school. Tests are designed to gauge how much of the material you understand, track your progress, and make sure that you fully comprehend everything that you have been given over a long period of time. In a medical emergency, answering a question is not about comprehension or understanding material. It's about how to react to a situation. Surely students are not that stupid as not to know the difference between saying "I don't know" on a test, where they could be taking the lazy way out or just giving up too easily, and an emergency, where there is no need to attempt to guess?


Joe D

In Australia there's a country wide Primary/Secondary school mathematics competition that has used a similar system, they've jigged it a few times but it always involved the same concept of penalising random guessing.


Tim McCollough

Hey Freakonomics community!

To clarify, the -1/4-pt. wrong answer, +1/4-pt. "I don't know" system is for the multiple choice section of quizzes. My students are college-bound juniors and seniors. Mathematically, this works out so that students should only guess if they can narrow the answers to two choices. Result: less blind guessing (and more honesty).

The IDK response also gives me valuable data as a teacher. Knowing which questions resulted in the most IDKs provides instant feedback to which concepts need immediate re-teaching; and knowing which kids wrote the most IDKs tells me, with more accuracy, who is underachieving and what their needs are.

re: James' comments, this system doesn't alter the incentives for students to learn and "get it right." If a student does nothing and guesses at every question, she'd get 25% of all questions correct by random chance in a normal system. Under my system, she could write IDK for all questions, and get the same 25%. The difference: I know exactly what she "does not know."

- Tim

PS When I give retakes, I take the average of the retake grade and the original score. This way, students can improve their grade with improved understanding, but are still held accountable for their first failure.