Karen Jones had spent the past five years of her teaching career in a suburb of Buffalo, New York, being bounced from school to school and subject to subject like a ping-pong ball. Significant state budget cuts in 2013 that laid off teachers, increased class sizes, and cut services, coupled with Jones’s lack of seniority (she was among the newest, though she’d been at it for 12 years), meant she was among the first to be sent to fill in the staffing gaps.

After eight years teaching upper-intermediate math, she was moved three times in three years, first teaching fifth-grade math, followed by kindergarten, and then, amazingly, back to fifth grade — all at different schools. She considered herself lucky that she still had a job.

Then, last spring, Jones was laid off. She was expecting to be without a job come fall, only to be called back to the classroom that same June, at the very end of the school year. Jones was somewhat relieved until the district presented her with more bad news: If she wanted to keep her job, she’d be required to move positions — again.

At that point, after talking with her husband, manager of a local business installing car locks, Jones, 34, decided enough was enough. She would take a yearlong sabbatical, which was within her rights according to her contract, to decide what she wanted to do. If she wanted to return to teaching after that, Jones knew her job would be there for her — unless they laid her off again.

She knew the loss of income wouldn’t be an issue for her family if she decided not to return. For the last three years of her unstable teaching career, Jones had been steadily growing a side business, selling curriculum units and related classroom material she created on her own for the online marketplace Teachers Pay Teachers.

In fact, at the time she got laid off, Jones was making more money selling her lessons to educators on Teachers Pay Teachers — “TpT” to those in the know — than she was getting paid for actually teaching them to students.

OOf the 186 products Jones has available in her online store, her most popular is the Ultimate Printable Phonics Pack, which sells for $10, twice the amount of TpT’s average sale. Jones created it while teaching kindergarten, working nights and weekends over several months to organize the activities she was using with her students into a sellable format. She’s sold more than 8,000 units in the two years the pack has been available in her online store. The product description promises 80 pages of ready-to-print phonics activities meant to help kindergarten and first-grade students learn the sounds of alphabet letters and attach those sounds to letter names — considered one of the first and most crucial building blocks of reading.

The phonics pack has nearly 2,800 customer ratings and an overall four-star rating — TpT’s highest — with many gushing comments from teachers who used and loved it. “This pack is AWESOME! These are great for so many things! I can use them during stations, for homework, for morning work. LOVE LOVE LOVE this!” wrote Laurie S.

Laara N. wrote, “I love the clipart and layout you use. The pages are very user-friendly! I have your Elf packet and my students loved it. I know they will love this packet just as much! Thanks for sharing your talent!”

Jones got the idea to open a store just over three years ago. She had been moved from middle-school math to kindergarten general ed and had to begin planning lessons from scratch. She said it was like starting a brand-new job but with no training. “I was moving to a new school and didn’t know anyone. It wasn’t like I could lean on colleagues to help me out. So, kind of out of desperation, I was searching on the internet and found Teachers Pay Teachers and found a couple of units on there, and I thought, wow, this is really great for someone who is totally unfamiliar with their grade level.”

Evidently, even teachers who aren’t starting from scratch and have been teaching the same grade level for years are finding materials — lessons, task cards, activities, quizzes — on TpT. Created in 2006, TpT is the brainchild of Brooklyn middle-school teacher Paul Edelman. Today, the site has more than 1.8 million resources and 3.5 million active members — buyers and sellers mostly from the United States, but also from the UK, Australia, and New Zealand.

In August 2015 alone, more than one in three American teachers marched back into the classroom with something they had purchased from TpT, making it likely that as you read this, your children may be coloring a worksheet or taking a quiz their teacher purchased on the site with their own money.