Quizlet - The World's Largest User Generated Learning Platform

On the occasion of our portfolio company Quizlet‘s announcement of a new round of funding today, I thought I’d talk about what led us to Quizlet and why it is poised to be a game changer in education.

Quizlet is the world’s largest user generated learning platform. Founded in 2005 in founder Andrew Sutherland’s bedroom (he was 15 at the time), Quizlet has become the wikipedia of the education sector. Over the last twelve and a half years, users have posted over 200 million study sets to Quizlet. A study set is a list of things you want to learn. Think of what happens when flashcards meet the Internet and mobile devices. A study set can be French Adverbs or Heart Muscles or a Pre-Takeoff Flight Safety Checklist. You can study these things anytime and any place that you have a mobile phone on you.

That was all already in place when we invested in Quizlet in the fall of 2015. I wrote this post talking about Quizlet at the time.

What wasn’t there, and is now, is the machine learning team to make sense of all of these study sets. Take 200+ million study sets and 30+ million monthly users and you have a ton of data about what people are learning, how they are learning, and how their learning evolves over time on Quizlet. From that data will come new modes of learning on Quizlet and a lot of help figuring out what study sets are best to learn something.

The other place Quizlet plans to invest in is expanding Quizlet internationally. Over the last year, the Quizlet team has localized into 18 languages. Now, over 90% of the world’s population can use Quizlet. And because Quizlet is free to use for everyone, that means this user powered learning model can be used by students all over the world. Quizlet intends to aggressively expand its content base and user base internationally in the next few years.

Just because Quizlet is free for anyone to use doesn’t mean it is not a good business. Quizlet has two primary revenue streams right now, advertising and subscriptions, both of which are performing very well and there will be more revenue opportunities for Quizlet as they build out their content base and user base around the world. Quizlet was a profitable business when we invested in it back in 2015 and has remained at or near profitability even with the significant investment we have made in the business since then.

Quizlet is a great example of how you can build a very good business while expanding access to knowledge dramatically around the world. One does not have to come at the cost of the other if you architect your product and business model appropriately.

#hacking education

Comments (Archived):

  1. JimHirshfield

    Wow. So surprising what 15 year old boys do in their bedrooms.

    1. fredwilson


      1. JamesHRH

        The highest of compliments earned – the IWIHST.

      2. sigmaalgebra

        Adolescent boys need good information on both male and female anatomy including all the parts and pieces. Attaching guilt, shame, immorality, and lots of illegality, etc. is a brain-dead sickness that the US pursued far too long and that caused a lot of problems for no good reasons.Boys grow up fast and in their teen years have some severe, fundamental problems getting any reasonable understanding of or insight into females: E.g., girls and women do a LOT with non-verbal communications; to be good husbands and fathers the boys need to learn about such communications, but most boys can’t learn about that at all well from girls their own age at school, and a lot of boys don’t learn it well at home. A big reason the boys are short on good opportunities to learn what they need to know is the guilt, shame norm. For much more, mostly the females outside their own families the boys meet are just the girls the same age in school. However, very strongly the teenage girls have contempt for boys their own age and, instead, e.g., Lady Di by age 15, are very interested in boys/men 1, 2, 4, 5, 10, 15 (the case for Lady Di) years older — a good family, education, income, car, house, and maybe a boat all help a LOT. I know; I know; our society regards a case of a girl 15 being interested in a man 30 as a reason to lock up the man, write the most ugly condemnations, at least throw him out of Congress, etc.Much, maybe most, US culture is hung up, say mixed up, on S.E.X.I’m not saying that a good solution is trivially simple, but the US needs a much better solution.

    2. Richard

      COPPA regs

    3. JamesHRH


  2. jschless

    How do you view/compare Quizlet (which, admititedly, I’ve never used) to Duolingo’s Tiny Cards?I’ve begun to use Tiny Cards a bit, and love the sets created by [i think] the Duolingo team. High quality design and a genuinely intuitive and helpful product. The design reminds me of a gem of a YouTube channel – Kurzgesagt: In a Shell (https://www.youtube.com/cha

  3. jason wright

    my kingdom for a classroom, not bedroom or boardroom.there’s no substitute for learning with others in a shared physical space. it’s social, it’s natural.

    1. MargaretR

      It can be a great complement for the classroom. My daughter uses Quizlet to prepare for tests and exams. Especially French.

      1. PhilipSugar

        I could not agree more.

  4. Donna Brewington White

    Bravo for Quizlet! A household word in my home.I have a goal to transform my lycée français to fluency by late summer. The USV portfolio will come to my aid, I’m sure.

  5. JamesHRH

    Pretty quiet day here in the saloon / salon. Maybe this will perk things up!http://knowledge.wharton.up…Basic conclusion is that corporate power rangers hold nearly identical values and beliefs, which means that gender, race, culture and religion cannot over come the discipline of profit and scale.Jordan B Peterson having a small episode over it on The Twitter.

    1. Lawrence Brass

      For me it is pretty simple. In a system or game designed mostly by men, men will always have an advantage as they wrote the rules with their male biases.The only way woman can have what they want and deserve at work is taking power away from men, by means of fair representation.50% female representatives at the house and congress, it is about time…. in exchange for recovering our say at home. 🙂

      1. JamesHRH

        I am not yet sure I agree w Prof Peterson, but his claim is that business success correlates mostly to the personality trait of disagreeableness.The idea is that willingness to ruffle feathers and not get along to get certain things done ( the right things, however you define right ) is critical………and that more men have that trait than women.Food for thought.

      2. sigmaalgebra

        > For me it is pretty simple. In a system or game designed mostly by men, men will always have an advantage as they wrote the rules with their male biases.In trying to be successful in “the world of work”, created almost entirely by men in ways that fit for men, women too often encounter unspeakable anxiety and hell.Your proposal of 50% female in Congress, etc. might be doable and have some merit for some short terms in some special circumstances.But mostly otherwise for the world of work, the men who do it well usually do it way over 40 hours a week, way over full time. They have a tough time getting away long enough to see their daughter in a ballet or their son in Little League.So, we can expect that women doing equally well in the world of work would need about the same time allocation. Then they will have a heck of a time being good mothers, and we can be 99% sure that their husbands won’t make good mothers! So, a woman fails at motherhood.Darwin is watching and won’t take such a failure lightly. So, the women doing well at work promise, on average, to be weak, sick, or dead limbs on the tree. Then in a few generations, Darwin will get his way: Nearly all the women left will have been from strong limbs on the tree — that is, from women who concentrated on motherhood and NOT the world of work — and will want to concentrate on, and may I have the envelope, please [drum roll, please], and the winner is MOTHERHOOD, and to demonstrate against this result we have Ms. Gloria Marie Steinem.Motherhood is darned serious stuff. Any woman who has done well at motherhood can be proud that they have done really well doing their part keeping civilization going and making the next generation better. Very little in the world of work is that good.”The hand that rocks the cradle rules the world.”For women to emphasize the world of work and “equality” would be a really big step down for woman, our society, and civilization.

        1. Lawrence Brass

          Yes, motherhood and woman’s love, unique treasures that only they have and carry.We will never be equal, among genres, races, cultures and individuals. We are all different. Diversity and change is reality.Rights and access should be equal.

  6. Jason Peterson

    Everything that I’ve read suggests that the act of creating your flashcards, and the concomitant deep thinking that goes along with, leads to retention. So that’s my main issue with premade cards. A cool feature might be if you had to answer the question correctly before you added it to your deck, to ensure you are adding knowledge just to refresh and not to learn

  7. sigmaalgebra

    I have to rush off to get dinner and then get back to assembling the parts of a server so will likely leave this post in need of revision.I’m all for “hacking education” and have done a lot of that for myself.And I believe that the Internet can be a great hack, disrupter, and step forward for education.So, in principle I should like Quizlet.I just looked at several of the Quizlet “study sets”.That they have such a good business is curious.But from the study sets I saw, the quality is horrible: Terrible errors and really bad writing are too common. More generally, too often the writers just don’t know what the heck they are writing about. I would say that no student trying to learn should look at the Quizlet content.For Quizlet has become the wikipedia of the education sector. I have to say nonsense: For topics covered well by the best US universities, Wikipedia nearly always has nicely high quality.E.g., from what I knew about the fast Fourier transform (FFT), I got a nice high end Camaro, some nice samples of grape juice from the Haut-Médoc and the Côte-d’Or , great times at Christmas, etc. E.g., a guy at the JHU/APL had built an FFT box. I met him just as he was done. I showed him a version of the FFT that had the same signal flow graph at each stage. After he picked his jaw up from the floor, he confessed that what I had shown him would have saved him a major fraction of the circuitry in his box.Well, athttps://en.wikipedia.org/wi…Wikipedia does well with the FFT. But Quizlet gets confused already with just the beginnings of trigonometry and thinks thatsin(180) = sin(π)which of course is nonsense because we are not clear on units, likely degrees on the left and radians on the right.It’s dirt simple, guys:180 = 3.141592653…is not even close to right!!!!!That’s MUCH worst than2 + 2 = 5Find some people with money who believe180 = 3.141592653…and we can make big bucks in a big hurry!Apparently Wikipedia has a relatively effective peer-review process, and Quizlet doesn’t.The Wikipedia of education is still Wikipedia.Maybe in time Quizlet will deploy good means of improving their content.Broadly, in education, quality is a big issue. The best of the content has most of the crown jewels of civilization, has nearly all of the best in quality, power, and value, and is readily available, now including often on the Internet. Still, especially on the Internet, there is a lot of JUNK also readily available.So, suppose someone is trying to learn:(1) The most important consideration is the quality of the content. So, the content has to be correct, and the writing has to be clear. Sadly, we can’t take high quality or even usefully high quality for granted and, instead, must look for it.Uh, learning anything significant is not a spectator sport and, instead, is a lot of work for the person trying to learn. Low quality materials are a waste of time and even harmful; relatively high quality is crucial.E.g., there is a book on optimization in finance and published by Princeton University Press. The book tried to be about applying the Kuhn-Tucker conditions. Well, I know some things about the Kuhn-Tucker conditions and published some associated research in JOTA. In trying to get through his book quickly, soon I ran into what looked like nonsense. So, I backed up and went through his first chapter carefully checking every claim, theorem, and proof. At the end of that chapter, I had constructed counterexamples for every claim or theorem in the chapter. Net, every statement in the chapter was false. Uh, I can get anyone a low price on a slightly used Princeton University Press book on optimization in finance!!(2) Next, the student needs good guidance to:(A) Be clear on what they are trying to learn and why.(B) Know what the prerequisites are.(C) Know what the applications are or might be.(D) Focus on the appropriate parts of the subject, e.g., by analogy, the trunk and larger branches, and not get lost in the whole. Getting lost is too easy to do.(E) Get good intuitive overviews, sometimes with pictures.(F) Find appropriate study materials.(G) Have good self-testing.(H) Have good means of getting good answers to questions.(I) See connections with other topics and known or possible applications.(J) See where the boundaries of the subject are and what points on the boundary are promising for progress.(K) Connect with people with related interests.(L) Often have some means of getting appropriate and widely respected certification.So, students need this help. So, how to have a good business providing that help?My view is that the first, main need is just finding the good content that already exists. A big challenge here is meaning, finding content with, e.g., (1) and (2) with (A)-(L) above.There really is a lot of good content; too often, finding that content is too difficult. So, right away, help people find the good content that does exist.Next, with good means of people finding good content, people who can develop more good content will be more highly motivated to do so, and there will be more good content.With more people eager to develop good content, monetizing that content will become easier which will result in more good content and, thus, increase the importance of finding that content and more people benefiting from it.

    1. Vasudev Ram

      >Wikipedia does well with the FFT. But Quizlet gets confused already with just the beginnings of trigonometry and thinks that>sin(180) = sin(π)>which of course is nonsense because we are not clear on units, likely degrees on the left and radians on the right.>It’s dirt simple, guys:Yes. that is quite simple. They should mention that 180 degrees equals Pi radians, what degrees and radians mean, and how to convert between them (which is obvious to anyone who knows algebra and the above equality between degrees and radians).

      1. sigmaalgebra

        Uh, be careful: Having π = 3.141592653 degrees is perfectly reasonable. So, insin(π) = sin(3.141592653)does not, Not, NOT, NOT really mean, imply, or show that the units are radians instead of degrees.To be clear, in trigonometry, if are working in degrees then must SAY SO, clearly, unambiguously, etc.So, the problem with that Quizlet was that the author just got it into his little, uninformed, misinformed, ignorant little substitute for a working brain thatsin(π)necessarily implied working in radians. WRONG. Badly WRONG.No way am I riding in a rocket designed by a engineer with such poor understanding of trigonometry. E.g., the engineer’s little pocket calculator, Python code, Mathlab work, etc. no doubt has a way to select beteen degrees and radians, and some poorly informed user can see π and conclude that the units MUST be radians which is FALSE.Crash, boom, smoking hole.So, a problem with Quizlet is that too many of the authors have poor, even dangerously poor, qualifications.Wikipedia has better peer-review. So, Wikipedia can get the FFT correct, and Maxwell’s equations, sufficient statistics, etc., and Quizlet already flops on high school or middle school trigonometry.I tried to explain these points. I focused on just one word — quality. Since there’s a lot of low quality out there on the Internet, to get needed, necessary, quality, we have to be careful and work at it.

        1. Vasudev Ram

          You don’t seem to have understood what I wrote. Read my comment above again; also I explain it in other words below:>>sin(180) = sin(π)And I had said:>Yes. that is quite simple. They should mention that 180 degrees equals Pi radians, what degrees and radians mean,By which I meant: if they wanted to use that equality above (with the two sin()s in it), they should have specified that the 180 on the LHS (Left Hand Side, math term, for others) was in degrees and the pi on the RHS was in radians, and that only then does the equality hold. Of course, normally one does not use different units on two sides of an equation, so they were wrong to start with.And BTW Wikipedia is not perfect either. They also have quality issues, vandalism of pages, slanted pages, etc. Just go through a number of pages there and you will see pages with comments like “Page issues” at the top, followed by some reasons why they think there are issues.

          1. sigmaalgebra

            I took your> (which is obvious to anyone who knows algebra and the above equality between degrees and radians).as claiming that it was obvious that insin(π)the units were radians. Okay, glad I misunderstood!Yes, Wikipedia is not perfect, and I never claimed it was. My claim was just that Wikipedia has an “effective” peer-review system, technique, process, whatever synonym, etc.My point was the comparison: Some high end trigonometry, i.e., Fourier theory, Wikipedia got okay, and some low end trigonometry Quizlet made a mess.The Quizlet error is elementary — let’s see a little of how elementary; I started in trigonometry in high school first year algebra. I took a one semester course in it as a high school senior. Of course, in college in math and physics, I was using trigonometry all the time. As a college senior I had a introduction to Fourier series. Then the first course I taught as a grad student was trigonometry for freshmen, and there the first test I gave had questions about converting between degrees and radians.Point: Being clear on degrees and radians is the first lecture or two in trigonometry.So, again, Wikipedia does okay in Fourier theory while Quizlet makes a mess in the first day of a course in trigonometry.Net, Quizlet has some serious quality problems and needs, say, some better procedures for quality control or some such.By the way, occasionally there are also errors in some of the best math and science texts and in the peer-reviewed journals.So, errors, errors, there are errors everywhere, but the difference in errors and quality between Quizlet and Wikipedia is too large.Maybe some French adjectives are good on Quizlet, but from what I did see I’d advise any student trying to learn any academic subject to avoid Quizlet.But I would also advise any student who wants to learn calculus to avoid high school AP calculus: The time I looked at the AP materials, I concluded that the writers didn’t understand calculus very well. But the world and likely the used book collections are awash in beautifully polished texts for freshman calculus. Want to learn calculus? Get 1-3 of the most popular texts of the last 50 years. say, used and cheap, and dig in.Dig in? I did that for freshman calculus: I never took such a course and, instead, got a good book, dug in, started on sophomore calculus, and did fine.Point: Dig in is fine; learning calculus from a good book is very doable.At least at times, Khan Academy has tried to teach calculus. The time I looked, again, I concluded that Khan Academy didn’t understand calculus very well.I’ve studied calculus, advanced calculus, applied advanced calculus, real analysis, functional analysis, numerical techniques in calculus, and well beyond, taught calculus, applied calculus in academics, business (once saved FedEx with it), and in US national security, and published peer-reviewed original research in it. With that background, I have some insight and overview of calculus and are qualified to have some opinions about quality. Still, for a good first book in calculus, I’d look for an author with a better background than I have.For AP and Khan, they are part of the bad news.Quality is crucial and in the main academic subjects readily available at low or no cost. Students need to be told this.

          2. Vasudev Ram

            >the units were radians. Okay, glad I misunderstood!Yes, I get you now. My first comment was not 100% clear and made an assumption that the reader would get what was partly unsaid about the sine stuff. NP.You make some good points in the rest of your comment above.Surprising if Khan Academy calculus topic is not good. Sal Khan himself is very qualified, I’ve read. Maybe that part was written by someone else or it was a QA slip.Maybe you should ping them and point out where you think there are issues in the content.

        2. Vasudev Ram

          >I tried to explain these points. I focused on just one word — quality. Since there’s a lot of low quality out there on the Internet, to get needed, necessary, quality, we have to be careful and work at it.I agree, there is a lot of low quality stuff out there.

  8. DJL

    Congrats to the team and USV! Quizlet is becoming like “google” and “Siri” to my kids. Just a common name for online quizzing.That being said, I echo some of the comments below on quality. What is REALLY needed is for special curators to choose from all of the Content and create specific sets for Grade 1, Grade 2, etc. and then promote to school systems. Putting together learning sets seems like composing a movie from 100 different YouTube vidoes. Teachers do not have the time or knowledge to do this.

    1. PhilipSugar

      The problem is while I think the vast majority of teachers are GREAT. The vast majority of administrators are BAD. And they make the decisions.So it is hard to do, because the administrators don’t want it. Threatens their job.Look up so many school districts. The administrators outnumber the teachers. CRAZY. There was one district where the number of administrators doubled while they cut teachers, and then said we have to drop electives. I know who we need to drop.

      1. DJL

        Agree 1000%. They are like mini US governments where the Admin is Congress.

        1. PhilipSugar

          I don’t think it is about Congress as much as Government Workers. Now of course you can say it is the fault of elected officials and you are right.What incentive do they have to take on Government workers?Think about any business. How many admins do we have? Practically none. Then go into a government office, almost 1 to 1 ratio. In 21 states there are more administrators than teachers. https://www.washingtontimes…All of these tools are awesome. No teacher should feel threatened. Every administrator should.I told everyone I had a business partner decide to takeover the PTA. What he found was unbelievable. Things like a secretary making $89k in Pittsburgh with full pension and he said he never saw her, but they wanted to give a raise or she would quit. Things like buying a new super expensive John Deere lawnmower that was so big they had to build a new garage for it, and the guy using it super expensive. The cost was about the same as 20 years of commercial grounds service.Edit: And that district had said they needed to cut band, art, and physical education due to budget reasons.

      2. Vasudev Ram

        Been reading similar stuff on HN in posts about US universities. Sad to hear this. For the previous generation or two to mine, the US was known as the land for higher education.

        1. PhilipSugar

          Top learning…..no better. Lower not so much.

  9. marcoliver

    How many paying users do they have? And why after 17 years do they still need funding?

  10. maxniederhofer

    Super cool. Glad to hear they’ll be around for a long time!

  11. PhilipSugar

    Wikipedia, Khan Academy, and Quizlet, Online Lectures have done AMAZING things to enhance the classroom.I truly believe in the classroom, I think teachers are doing God’s work. They cannot be replaced.These tools have revolutionized how we can have shared learning with others in a physical space.If I go to a classroom and the teacher lectures for the entire time is that social or learning? Instead I can watch the best lecturer in the World on the subject, or watch a lecture from Mr. Khan, or lookup a fact on Wikipedia, or study my flashcards with Quizlet.THEN in the classroom I can do what is truly learning: discuss and unlock knowledge with my fellow students and teachers.These tools have allowed us to do what you could only dream of when I went to school: Instead going to a classroom and not having interactions and then go home and study, you can do the opposite: Have interactions in the classroom and go home and listen or work with lectures.My brother says it best. He has been voted the top professor at the largest engineering school in the U.S. several times. When it comes to robotics there is none better.But he says there is a professor at Georgia Tech that is AMAZING at controls theory. He can have his students watch his lecture at home and then they can work on and apply in his classrooms and labs.

    1. Vasudev Ram

      Good points. Kind of ties into Flipped Learning.https://en.wikipedia.org/wihttps://flippedlearning.org/In the Wikipedia article above, the section titled “In Practice” is particularly interesting. Look for the paragraphs that start with:”In 2011 educators in Michigan’s Clintondale High School flipped every classroom.”