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I've been teaching high school math for over 25 years. I write about my experiences here and also share activities that I have done with my classes that have been successful (and some that have been not so successful).

History of DeltaMath

If you are a secondary math teacher, you have probably used DeltaMath.com.  If you haven't, what are you waiting for?! Go create an account today. You and your students will love it.

If you are a regular DeltaMath user, perhaps you have asked yourself these questions: 

"Who is the mastermind that came up with this?"

"How is this free!?"

"Why are there no questions that cover X topic?"

Check out my related posts: What DeltaMath Can and Cannot (Yet) Do and How to Use DeltaMath

Having been an avid DeltaMath user since 2017, I have asked myself these questions many times. Recently I asked them to the mastermind himself, the creator of DeltaMath: Zach Korzyk.

Knowing that Zach is active on social media (follow him on Twitter @MrDeltaMath), I recently contacted him through his DeltaMath Facebook group and asked if I could send him a few questions about the history of DeltaMath because I wanted to feature him on my blog. He was quick to respond and was very generous with his answers. See below.

When did you start DeltaMath?

I started DeltaMath in 2009 during my third year of teaching. I made DeltaMath Plus* an option in February 2020 in anticipation of needing an income from leaving my teaching job.

*DeltaMath Plus is the optional paid subscription service; it's very reasonably priced and very valuable.


Why did you start DeltaMath?

I gave a quiz on the quadratic formula and I noticed that about 50% of my students were making mistakes either (1) setting the quadratic equal to zero or (2) finding the discriminant properly, especially when b was negative. I had a background in computer science from college, so I decided to make a randomized set of problems where the students simply had to find the discriminant value. 

There were no databases or accounts. If they got five in a row correct, it would send me an email with whatever name they typed into a box. The students completed the task, I regave the quiz, and there were nearly 0 mistakes. 

At that moment, I knew what I had to do. I devoted nearly all of my free time to building an interface for my students to practice a higher variety of problems. By the beginning of the 2010-11 school year, I totally revamped the application using JavaScript and opened it up for any teacher to make an account and use for free with their students. 

How long does it take you to create one module?

There is a huge variety of modules there. Some of the non-graphical, non-interactive modules may only take 2-3 hours to make. Still, the newer two-column proofs, for example, took months to develop due to their complexity and variety. 

While teaching, most times I was making modules on a tight schedule, trying to get things ready to use in my class each week, so I may have skimped on giving each module the proper variety. 

Later on, when more and more teachers were using DeltaMath, I would spend longer on modules to make sure they were of the highest quality with significant variety to challenge students.

How many people are on your team now?

Up until August 2020, I was the only full-time person working on DeltaMath. However, once I saw that many schools were purchasing the premium DeltaMath Plus for the fall, I was confident enough to make some hires. 

In the last five months of 2020, I was able to hire five new people full-time, four of whom are former teachers as well. We also have three part-time / contractors working on customer service and module development. I'm happy to say that about half of our team's effort is focused on content development, which benefits both the free and premium users. 

I am still the sole person responsible for the development of new features, backend servers, and the user interface, but we hired our first senior software engineer in December 2020 who will soon be able to help in that area as well. For the time being, though, he will have to help me reorganize this behemoth application and code base that was incrementally developed over 11 years.

How many teachers have an account?

There have been 154,000 teacher accounts created since the beginning, but many were never used. As far as active teachers, almost 50,000 have used the site in the last month. 

As far as student accounts, there have been 6.2 million created since the beginning, with 2.2 million using it in the last month and about half a million on a typical school day. 

This would have been beyond my wildest imagination in the first year DeltaMath was open to the public. In that first year, 137 teacher accounts were created, and 1.1 million problems were solved all year, and I was beyond excited. Now, on a single school day, over 300 new teacher accounts are created, and more than 6 million problems are solved. 

Did you have any idea how much teachers would love DeltaMath when you created it?

Honestly no. I mainly made it for my own purposes and let other teachers make accounts just in case a few other people might find it useful. Each year, seeing the growth from the year before always took me by surprise. 

As a teacher, I always asked myself if another product came out that I deemed would be better for my students, would I stop using DeltaMath? In theory, I thought I would, and I assumed something great had to be out there, but it never came to that. 

Any program I tried never gave me enough control, the problems weren't rigorous enough, the explanations weren't clear enough, or the interface was confusing to use. When people ask, "what makes DeltaMath special?" I honestly don't know what to say. It's not that complicated. It just works, and it helps students learn, and I guess a lot of other teachers would agree.

Was it a difficult decision to leave the classroom? Did you feel that you had a lot of support when you made that decision? Any regrets about leaving?  

I really loved teaching, and I waited until the latest possible moment to leave. I started the 2019-2020 school year thinking it would probably be my last year teaching, considering how much time I was spending on DeltaMath. 

Then having another 150% increase in the fall, I was spending hours per day answering teacher questions, fixing bugs, and making sure the server stayed healthy with the high levels of usage. I decided it was untenable for me to go on, and my last day teaching was the end of February 2020. 

It was very difficult telling my students I was leaving, but they were very supportive. I had two sections of AP Computer Science and two sections of AP Calculus, and I agreed to teach them "remotely" by making videos until the AP Exams in May. As it turns out, three weeks later that's what all teachers were doing, so my students didn't really miss out too much. They ended up doing great on their AP exams, so I have no regrets.

What are your long-term plans for DeltaMath?

Considering how much progress has been made in the last 10 years with just one person, I am so excited about what kind of progress we can make over the next 10 years with a growing team. 

Clearly, we have a lot of work to do filling out the content so that whatever a teacher is teaching, DeltaMath will be available for them if they want it. I also want to increase the number of interactive and graphical modules that can really help students visualize and grasp a concept. Considering the number of brilliant teachers and programmers we have on staff, the possibilities are really boundless. 

We will always listen to teachers and students to improve the design and interface to be more intuitive and easy to use, but the most important thing will be to continue to innovate. I have been asked so many times, when will DeltaMath "be done"? Never, and that's the most exciting part. 

If you would like to know more about Zach and see him in action in his classroom, check out this video interview with him which was filmed around December 2019 after he won the Sloan Award for Excellence in Teaching Science and Mathematics - an annual awards program that honors exceptional math and science teachers working in New York City’s public high schools.

A huge thanks to Zach for being so generous with his time in answering these questions and in creating DeltaMath, which has been such a lifesaver for so many secondary math teachers - especially since the pandemic started. You can follow Zach on Twitter @MrDeltaMath.

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