MAPLETON, N.D. — One of the tech-savviest teachers in the United States teaches third grade here at Mapleton Elementary, a public school with about 100 students in the sparsely populated plains west of Fargo.

Her name is Kayla Delzer. Her third graders adore her. She teaches them to post daily on the class Twitter and Instagram accounts she set up. She remodeled her classroom based on Starbucks. And she uses apps like Seesaw, a student portfolio platform where teachers and parents may view and comment on a child’s schoolwork.

Ms. Delzer also has a second calling. She is a schoolteacher with her own brand, Top Dog Teaching. Education start-ups like Seesaw give her their premium classroom technology as well as swag like T-shirts or freebies for the teachers who attend her workshops. She agrees to use their products in her classroom and give the companies feedback. And she recommends their wares to thousands of teachers who follow her on social media.

“I will embed it in my brand every day,” Ms. Delzer said of Seesaw. “I get to make it better.”

Ms. Delzer is a member of a growing tribe of teacher influencers, many of whom promote classroom technology. They attract notice through their blogs, social media accounts and conference talks. And they are cultivated not only by start-ups like Seesaw, but by giants like Amazon, Apple, Google and Microsoft, to influence which tools are used to teach American schoolchildren.