New version of the Slader iPhone app!

We’ve released a new version of the Slader iPhone app - and it’s FREE and AWESOME. Download it now!

New features:

  • Place bounties!
  • Buy gold in-app!
  • Upload photo solutions!
  • Improved graphics and layout!
  • Much much more!

School’d: Trick or Treat

School’d is a series about the data we collect at Slader and what we’re learning from it.

Some of this data is pure novelty - fun stuff that we’ve become experts in from spending hours with our site and observing our users’ behavior.

Other learnings seem more significant - not just in terms of how we run our site, but in regards to how students today are learning, and how they’re using the Internet to support their learning.

Hundreds of thousands of students visit Slader.com each week to help them with their homework. They are here by choice, not at the urging of their parents, their schools, or their teachers, and they’re taking a proactive approach to their own learning.

What can we learn from them?

Some teachers realize that students aren’t going to have time for homework on Halloween. Others don’t. It’s much better when Halloween falls on a Friday or Saturday!

Peter Bernheim is CTO of Slader.com. Questions? Comments? Something to add? Email me at peter.bernheim@slader.com

School’d: Textbooks over time

School’d is a series about the data we collect at Slader and what we’re learning from it.

Some of this data is pure novelty - fun stuff that we’ve become experts in from spending hours with our site and observing our users’ behavior.

Other learnings seem more significant - not just in terms of how we run our site, but in regards to how students today are learning, and how they’re using the Internet to support their learning.

Hundreds of thousands of students visit Slader.com each week to help them with their homework. They are here by choice, not at the urging of their parents, their schools, or their teachers, and they’re taking a proactive approach to their own learning.

What can we learn from them?

Since most of our content at Slader is based on textbooks, we’ve learned a lot about the textbook industry, the key players (publishers and authors) and the way that textbooks change over time. New editions of textbooks are released every few years, often with very little changed except a problem here, or a new state standard addressed there.

Below, I take a quick look at the way that two textbook families have changed over time. The families include everything from state-specific versions of a textbook to truncated versions of the same material, as can be seen in the varying lengths of the books shown.


Book 1 above is a popular upper level textbook family. While newer versions of this book have been introduced recently, it’s clear that many students are still using older versions. It’s common for books upwards of 10 years old to still be quite popular, especially with upper level math; the state standards are less subject to change, plus I’d guess the students tear out and doodle on pages less often.


Book 2 is a lower level textbook. More users have clearly shifted to the latest edition, with just a few using the older versions of the books.

While not surprising, it’s interesting to see how clearly page counts map to exercise counts, even across Book 1 and Book 2. Also worth noting (though not clearly seen here): even though textbooks change often, many of the exercises stay the same year after year, just wrapped in a new shiny cover.

Peter Bernheim is CTO of Slader.com. Questions? Comments? Something to add? Email me at peter.bernheim@slader.com

School’d: Predicting student failure - an introduction

School’d is a series about the data we collect at Slader and what we’re learning from it.

Some of this data is pure novelty - fun stuff that we’ve become experts in from spending hours with our site and observing our users’ behavior.

Other learnings seem more significant - not just in terms of how we run our site, but in regards to how students today are learning, and how they’re using the Internet to support their learning.

Hundreds of thousands of students visit Slader.com each week to help them with their homework. They are here by choice, not at the urging of their parents, their schools, or their teachers, and they’re taking a proactive approach to their own learning.

What can we learn from them?

We often say that the data that we collect at Slader allows us to ‘predict student failure’. By this, we mean that by looking at a student’s behavior on Slader, we develop an understanding of problem areas and concepts that challenge them more than others. And, based on data patterns, we can use this history to predict the exercises/concepts which they will, in the future, have trouble with.

Knowing this information can provide a number of opportunities:

  • offer additional resources that might aid this student
  • predict exercises they might have trouble with
  • suggest practice problems/tutorials around the areas with which they are having trouble

One of our core beliefs at Slader is that students seeking homework help online probably don’t know what concepts they’re struggling with - they just know they are struggling. Our solution product aims to offer help exactly where they need it, the homework they’re tasked with completing on a given school night. If we can assess trouble areas and understand where a student is heading, we can help them to brush up on concepts or techniques which they might not even know they are struggling with. The first step in getting help is to identify what you need help with - that’s where we are heading with this data.

As we develop these features and refine our algorithms, I thought that sharing some background behind the data we are using and what it tells us might spark some good discussion.

I’m heading back to Stewart Calculus, one of our most popular books. Looking back at a popular, and often challenging problem from an earliest post, we’re going to look at Page 151, exercise 29.

I pulled a set of users who had trouble with this exercise, both showing a higher view time than their average time spent with a solution, and who spent more time than their peers. A rough breakdown of how these students’ time is spent is shown in Fig. 1 below.

I’ve filtered out views that seemed extra long here - students are a distractable bunch, and most likely that wandered off to Tumblr or Facebook and lost track of time. So, extra long view times are omitted. Once those outliers are pulled out, we get a fairly good chart of median (blue) and mean (red) solution view times. I used this data to understand how best to evaluate whether or not a user was finding a specific solution challenging.

For simplicity, I’ve further narrowed the dataset for this post based on users who spent more than 425 seconds with Pg. 151, Ex. 29 AND who spent more than their average time with the solution. For each of these users, I then pulled their histories for two weeks: Sept. 22 and Oct. 13. This allows a concentrated pool of exercises to look at. For all of the exercises viewed, I then mapped out the exercises which challenged these users both prior to and after viewing exercise 29. This resulted in Fig. 2.

We see a long tail of exercises that challenged just a few users. And a small set of exercises jump out as being challenging to a large group of users at the right edge of the chart.

Here are three examples, one from earlier in the book, one from the same problem set, one from later in the book:
Page 128, Ex. 41
Page 150, Ex. 5
Page 182, Ex. 51

What similarities can we see in these exercises? Why were they all so challenging to this group of students?

Ex. 41 on Page 128 involves understanding the graph of a function and where the function is discontinuous. Ex. 5 on Page 150 involves finding a tangent line to a curve. Ex. 29 on Page 151 finds the limit of a function (aka the line tangent to the curve at a point). And Ex. 51 on Page 182 asks for the horizontal tangent line of a curve. See any patterns? The prompts on Page 150 and 182 are nearly identical. And the concepts involved in all 4 are closely related. These students need some practice with visualizing functions as graphs and understanding the tangent lines along those graphs. With some added practice, we might be able to head off issues with these same concepts down the line.

The end goal of predicting student failure is preventing it - if we can see trouble before it happens, we can proactively help these students succeed.

As educators, what sort of data would be useful to you in predicting student failure? As a student, what might be useful information to help your studies?

Peter Bernheim is CTO of Slader.com. Questions? Comments? Something to add? Email me at peter.bernheim@slader.com

Slader in PandoDaily

Slader: The “cool” homework help platform that your mom doesn’t know about (via Pando Daily)

By Cale Guthrie Weissman On October 11, 2013High school homework is one of those shitty things most people are glad they no longer have to endure. For me, the bane of my existence was always AP Physics. Not only did I not understand the subject, but…

School’d: Odds or evens, by the numbers

School’d is a series about the data we collect at Slader and what we’re learning from it.

Some of this data is pure novelty - fun stuff that we’ve become experts in from spending hours with our site and observing our users’ behavior.

Other learnings seem more significant - not just in terms of how we run our site, but in regards to how students today are learning, and how they’re using the Internet to support their learning.

Hundreds of thousands of students visit Slader.com each week to help them with their homework. They are here by choice, not at the urging of their parents, their schools, or their teachers, and they’re taking a proactive approach to their own learning.

What can we learn from them?

Timeframe: the 24 hours from October 1 12:00a through 11:59p.

Most textbooks show the odd numbered answers in the back of the book. Some teachers only assign odds - so students can check their answers in the back of the book. Other teachers only assign evens.

But what homework problems are students actually viewing on Slader? This is helpful information for us at Slader, so that we know what users will be looking at on the site. With over 2 million unique URLs on Slader, it’s helpful to know where we should focus our resources.


Fig. 1 shows the split of views of odd problems vs. even problems on this night. It’s almost equal - users viewed odd problems as much as they viewed evens.


In Fig. 2, we can see that there are small groups of users that only view odd problems, and others that only view evens. But the majority of students are viewing both.

Only odds has a slightly larger slice of the pie than does only evens, but not enough for us to really call attention to the difference.

This is a very high level view of this information. It’d be interesting to break these numbers down with a larger dataset. We could examine how the cumulative time breakdown differed between odds and evens, or if patterns continued for a user throughout a schoolyear - showing that a specific teacher only ever assigns odds, or only ever assigns evens.

Based on the above numbers, though, it would be safe to say that just because the odd number answers are in the back of the book, doesn’t really affect what students are viewing on Slader.

Peter Bernheim is CTO of Slader.com. Questions? Comments? Something to add? Email me at peter.bernheim@slader.com

An interesting post on ‘flipping’ a classroom on the NY Times Opinionator blog.

Many of the drawbacks of traditional homework that are mentioned in this article are the same problems that Slader sets out to solve.

Some quotes that stood out:

"Many students do not ask questions in class, worried they will look dumb". Students on Slader benefit from the relative anonymity of the Internet to ask any question they have, and a lot of them do - it’s safe, their immediate peers are nowhere in sight, and they can get the help they need while they are doing their homework.

Luwayne Harris, a senior, complained that “whenever I had a problem on the homework, I couldn’t do anything about it at home.” Obviously, she doesn’t know about Slader - that’s what we, and the other students are on Slader for - ask a question about your homework problem, or just view our step-by-step solutions, with explanations, and this problem is solved.

And teacher Robert Townsend says, students “may have no support or help at home or live in a chaotic house. If they get stuck on the first problem they are out of luck.” Not with Slader.

School’d: Are high school students getting enough sleep?

School’d is a series about the data we collect at Slader and what we’re learning from it.

Some of this data is pure novelty - fun stuff that we’ve become experts in from spending hours with our site and observing our users’ behavior.

Other learnings seem more significant - not just in terms of how we run our site, but in regards to how students today are learning, and how they’re using the Internet to support their learning.

Hundreds of thousands of students visit Slader.com each week to help them with their homework. They are here by choice, not at the urging of their parents, their schools, or their teachers, and they’re taking a proactive approach to their own learning.

What can we learn from them?

No, they aren’t. It’s a common topic of discussion, with many articles documenting our sleep-deprived teens. We thought it’d be fun to see what the data at Slader has to say.

We don’t keep track of eye movements and we can’t capture a nap on a keyboard, but we do know when students are using Slader. Comparing this to high school start times and well-publicized studies on how much sleep teens should be getting, we can arrive at some broad (if not wholly scientific) conclusions.


Let’s set out our givens:

  • most high schools start at 8:00 AM, as reported by our users. Some teens have to arrive at school by 7:00 AM or earlier - insanity!
  • most teens require ~9 1/4 hours of sleep each night, according to the National Sleep Foundation
  • provided the average teen needs to roll out of bed, eat some breakfast, primp a bit, and then actually get to school, realistically, I’ll assume they wake up sometime between 6:30 and 7:00 AM. Though I’m sure it’s earlier than that for some students who have long commutes or exceptionally long grooming rituals.
  • we’re looking at all of the school nights September 22-26, 2013
  • this data is filtered relatively well to only represent the high school population, as we know that a subset of Slader users are actually in college, and their sleep schedules are significantly different

Some interesting background on the data:

  • during this week, we had users consuming content from all 50 states, and the District of Columbia (plus about 40 other countries)
  • the five most popular states for Slader during this week were (in descending order): CA, TX, FL, NY, IN
  • during this week, 58% of students spent more than fifteen minutes on Slader on any given night and 40% spent more than 30 minutes

Based on our assumptions, an average wake up time of 6:45a and a full night’s sleep of 9.25 hours, that gives us a healthy bed time of 9:30p. So, any student who is doing homework after 9:30p is most likely not going to be getting a full night’s sleep.

Fig. 1 shows the time that students had their last activity on Slader. All of these times are normalized based on the student’s time zone. You can see that the prime time for students to be doing homework on Slader is right about 9:00p. It’s also interesting to see two other strange spikes around 11p and 12a - not sure why these occur, but perhaps we can investigate this in a future post - TV schedules?

So, assuming the users went to bed immediately upon logging off of Slader, we can say that 27% of Slader users don’t get enough sleep on school nights. Knowing that there’s also TV, Facebook, Twitter, Tumblr, text messaging and probably quite a bit of non-Slader homework to do, it’s safe to say the real number is much higher.


Fig. 2 shows three different sets of bars, for three different school-start times. The vast majority of students start school at 8a, so that’s where we have the most data. But, even in this chart, with the limited data that we have for users starting school earlier than 8:00a, we can see that they seem to finish up their homework a bit earlier in the evening. This would be an interesting dataset to examine over a larger span of time to see if the correlation stands up. If it does, it seems students have a fairly predictable spread between when they do their homework and when school starts the next morning. Note: the difference between the data shown in Fig. 1 and Fig. 2 is due to the limitation of only knowing actual school start times of a limited subset of Slader users who responded to our survey.


Finally, while far from scientific, we asked Slader users what they thought. As of the writing of this post, 91% of students using Slader feel they don’t get enough sleep. We also asked them what time they wished school started - almost all Slader users want to sleep an extra hour every morning, and move the average start time to 9:00 AM. According to our data, that could let at least another 11% of high schoolers get a full night’s sleep.

Peter Bernheim is CTO of Slader.com. Questions? Comments? Something to add? Email me at peter.bernheim@slader.com