NOTE: This is one of a series of ten blog posts on cognitive biases that have applications in education.

Have you ever gone to a movie theater, only to realize that the movie you hoped would be good was actually terrible? Perhaps you left the theater, but perhaps you stayed, thinking that you already paid for the ticket so you might as well get your money’s worth. This common feeling is called the sunk cost fallacy. The reality is that whether you stay or go, the money you’ve spent is already gone. Staying is not going to get that money back. Instead you are “throwing good money after bad” by giving up your time to a movie you don’t like.

Relationships are another all too common example. Many couples reach a point where they know they are better apart than together, but separating is akin to admitting that the time spent together was not leading where you both had hoped. The reality is that the time you spent together happened whether you break up or not. Continuing to stay together just means investing more of your precious time in a relationship that’s not meant to be when you could be exploring other options.


Implications for working with other teachers
This often happens in education, where teachers have invested significant time into the resources and lessons they use.  In theory, teachers would want to have a level playing field when evaluating the worth of a resource or lesson.  However, because of the sunk cost fallacy that just isn’t the case.  The resource you invested your time and energy into has an unfair home field advantage.  If we truly want to make objective decisions, this cognitive bias needs to be accounted for.

This is especially challenging in the era of the Common Core State Standards as teachers struggle to incorporate the new with the old. Instead of evaluating each strategy or lesson on its own merit and choosing the best one, they try to keep the old and also bring in the new. This creates a situation where they can’t possibly do all of what they hope for and struggle to keep up.

One hope for addressing this fallacy begins by acknowledging its existence and realizing that it always affects what we do. Choices will need to be made using more than our sentimental preference for the familiar. Just like with the status quo bias, questions like the ones below can be asked to help begin this process:

  • If you had never seen either option before, how could you tell which method would be most effective?
  • Why would someone use this option?
  • Why would someone use the other option?


Implications for working with students
The sunk cost fallacy negatively impacts students’ willingness to persevere through math problems. A normal part of the problem solving process is coming up with a strategy for working on a problem, trying it out, and making changes as needed until you reach an answer. What happens though when you become too invested in a dead-end strategy and would rather stick with it than let it go and acknowledge it was not the best choice?  The sunk cost fallacy may cause students to develop an unhelpful attachment to their own strategy and less objectively evaluate whether a new strategy is worthwhile.

One method for dealing with this reality is by having a class conversation to adjust student expectations.  Some students feel embarrassed by having an incorrect strategy.  Think about how many times you’ve seen a student turn in work that clearly shows much of the work erased so that it looked like the student got it right on the first try.  Other students, instead of covering up their tracks, might stick with a strategy they’ve invested their time into long after they should have given it up.  We need to talk about how changing strategies is a healthy part of the process.  Take every opportunity to praise the growth you see between strategies, especially when students have invested significant time and energy in the process.


What other instances of the sunk cost fallacy are you seeing?  How do you suggest we account for them?


  1. Interesting thoughts.
    One thing I’d like to think more about are the comparisons made between the movie attending, relationships, teacher choice, and student problem-solving. Are these fair comparisons?

    Could you explain the similarities and differences a little more. I feel some scenarios are consumption (movie-going), some are working at something (relationships and student problem-solving), and teacher resources require the exploration of cognitive bias, which I’d like to know more about.

    • Thanks for making me think more deeply. I guess the commonality is that they all require an investment of a resource that you value. With the movie, you invest your money and time. With the other three you invest your energy and time. All of funds for those investments were already spent. Nothing will change that. Now you have to decide whether or not to continue them.

  2. What a coincidence that you are exploring this idea in terms of education. Today I listened to an episode of Freakonomics Radio entitled “The Upside of Quitting” where they focused on the idea that quitting is often strategic and is sometimes the best plan. Give it a listen to hear more about the sunk cost fallacy.

    • Thanks Mitch. I’ve actually listened to the first 230 episodes or so of the Freakonomics podcast and read all of the books. I took a break for a while but hope to come back to that. I remember that episode well and especially the minor league baseball player. Definitely agree that there is a connection to this idea.

  3. I am thinking about how my feelings as a teacher seeong a student stubbornly clinging to an inefficient strategy are entirely different than my feelings about letting my favorite lessons go because they are no longer a focus in today’s standards.
    Maybe i need to have a little more patient understanding for that student, and a little less nostalgic decision making in my teaching choices.
    That being said, i am thinking about encouragements from elementary collegues about letting students move to more efficient strategies at their own pace of learning. Help me articulate how that is different/the same in our work with teachers.

    • Hi Leeanne. Thanks for your comment. I appreciate the challenge of working through old and new beliefs.

      I’m a little confused by what you are asking for at the end. Are you asking me to help you with something?

      • As i contemplated how to articulate my question, i think i gained clarity enough to answer it myself. So thank you.
        This was my puzzle:
        As a classroom teacher, i always felt pressure to move student learning at a predetermined pace to most efficient strategies. So much of what i have learned recently encourages me to respect the pace of each student’s own path from concept building to fluency. Now out of the classroom, i feel a similar pressure to move teachers to change instructional practice, which often includes letting go of favorite lessons or classroom structures, with little patience or repect for their own learning process.
        So my wondering was “Are these two situations equivalent? Do i need to defend both groups from this forced march to how someone else thinks they should do things? Or is it different because of the students effected by a teacher’s slow pace toward improving instruction?”
        My answer is “Lasting change in a person’s thought process will never be accomplished by someone doing the thinking for them. This applies to supporting teachers in their learning as well as students. It ok (actually necessary) to plan with patience differentiated learning opportunities to help teachers discover their need for moving from unweildy and ineffective practices.”
        And i think contemplating the sunk cost fallacy is an excellent step in this process. Thank you for the thought provoking piece.

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