Claire Mahler thought she’d blown it.

One student had squirmed in her seat. Others hadn’t grasped some of the more challenging concepts. Asked how she thought the sample lesson had gone, Mahler was honest: Parts had worked; others had not.

The next day, she received a call offering her the job.

Mahler’s experience is a familiar one at Cornerstone Academy Preparatory School. The sample lesson is a sort of audition required of every prospective teacher. They are given a topic, introduced to a group of students they’ve never met, and invited to teach, while several school leaders look on.

But it’s what happens afterward that matters most. “There is no such thing as a perfect lesson,” said Shara Hegde, the school’s founder and CEO. And so Hegde, who was joined in the back of Mahler’s classroom by the principal and academic director, wasn’t looking for perfection. Instead, she was eager to see how Mahler reflected on the lesson. Was she able to pick out the ways in which the lesson could be improved? Was she open to others’ suggestions?

“If you’re looking for a school that’s really going to serve your kids well, look for one that really supports their teachers well.” – Shara Hedge, Cornerstone Academy Founder and CEO
These questions matter at Cornerstone, where every teacher and leader (including the principal and CEO), meets weekly with a coach. Mahler describes the content of these meetings as “What’s going on and how can we improve it?”

Every Wednesday, students leave the school after lunch and teachers stay until 4 or 5 p.m. During this time, they co-plan lessons, meet with their coach, and check in about the school’s progress toward its ambitious academic goals.

“There’s this pervasive notion [elsewhere] that when you finish your student teaching, you’re fully baked and ready to go,” said Hegde. This notion didn’t sit well with her, so she founded Cornerstone in 2010 as a place committed to perpetual learning, for adults as well as students. Her rationale is simple: “If you’re looking for a school that’s really going to serve your kids well, look for one that really supports their teachers well.”

This assertion is borne out by the Cornerstone’s results. The school is increasingly attracting middle- and upper-income families, but it remains focused on low-income and minority students. Close to three quarters of the students are classified as low-income. More than half speak a language other than English at home—Spanish and Vietnamese in equal measure—and teachers are ever conscious of using approaches that will benefit English learners.


Data for 2014-15. From California Department of Education (CDE) downloadable research files for 2014-15 at

For these students (and for all students), Cornerstone is among the top-performing schools in the region. Last year, scores for low-income Latino students in English were 17 percentage points higher than the Bay Area average.

In that same year, Cornerstone received 240 applications for 60 available seats.

In Fall 2015, Cornerstone Academy launched a teacher residency program. Prospective teachers will earn their credential while student-teaching full time at the school. The program is being run in cooperation with Alpha Public Schools and the REACH Institute.

This article is part of our report, “How World-class Schools Deliver for All Students,” which includes our framework outlining six key practices that drive the success of the highest-performing schools. Explore the report to read more school profiles showing what these practices look like in action.