Key points:

When you walk into a math classroom in Charleston County School District, you can feel the difference. Students aren’t just memorizing steps–they’re reasoning through problems, explaining their thinking, and debating solutions with their peers. Teachers aren’t rushing to cover content, because their clear understanding of students’ natural learning progressions allows them to spend more time exploring the why behind the math.

This cultural shift didn’t come from adopting a new curriculum or collecting more data. Instead, we transformed math education by investing deeply in our educators through OGAP (The Ongoing Assessment Project) professional learning–an approach that has reshaped not only instruction, but the confidence and professional identity of our teachers.

Why we needed a change

Charleston County serves more than 50,000 students across more than 80 schools. For years, math achievement saw small gains, but not the leaps we hoped for. Our teachers were dedicated, and we had high-quality instructional materials, but something was missing.

The gap wasn’t our teacher’s effort. It was their insight–understanding the content they taught flexibly and deeply.

Too often, instruction focused on procedures rather than understanding. Teachers could identify whether a student got a problem right or wrong, but not always why they responded the way they did. To truly help students grow, we needed a way to uncover their thinking and guide next steps more intentionally.

What makes this professional learning different

Unlike traditional PD that delivers a set of strategies to “try on Monday,” this learning model takes educators deep into how students develop mathematical ideas over time.

Across four intensive days, teachers explore research-based learning progressions in additive, multiplicative, fractional, and proportional reasoning. They examine real student work to understand how misconceptions form and what those misconceptions reveal about a learner’s thought process. It is also focused on expanding and deepening teachers’ understanding of the content they teach so they are more flexible in their thinking. Teachers appreciate that the training isn’t abstract; it’s rooted in everyday classroom realities, making it immediately meaningful.

Instead of sorting responses into right and wrong, teachers ask a more powerful question: What does this show me about how the student is reasoning?

That shift changes everything. Teachers leave with:

• A stronger grasp of content
• The ability to recognize error patterns
• Insight into students’ conceptual gaps
• Renewed confidence in their instructional decisions

The power of understanding the “why”

Our district uses conceptual math curricula, including Eureka Math², Reveal Math, and Math Nation. These “HQIM” programs emphasize reasoning, discourse, and models–exactly the kind of instruction our students need.

But conceptual materials only work when teachers understand the purpose behind them.

Before this professional learning, teachers sometimes felt unsure about lesson sequencing and the lesson intent, including cognitive complexity. Now, they understand why lessons appear in a specific order and how models support deeper understanding. It’s common to hear teachers say: “Oh, now I get why it’s written that way!” They are also much more likely to engage deeply with the mathematical models in the programs when they understand the math education research behind the learning progressions that curriculum developers use to design the content.

That insight helps them stay committed to conceptual instruction even when students struggle, shifting the focus from “Did they get it?” to “How are they thinking about it?”

Transforming district culture

The changes go far beyond individual classrooms.

We run multiple sessions of this professional learning each year, and they fill within days. Teachers return to their PLCs energized, bringing exit tickets, student work, and new questions to analyze together.

We also invite instructional coaches and principals to attend. This builds a shared professional language and strengthens communication across the system. The consistency it creates is particularly powerful for new teachers who are still building confidence in their instructional decision-making.

The result?

• Teachers now invite feedback.
• Coaches feel like instructional partners, not evaluators.
• Everyone is rowing in the same direction.

This shared understanding has become one of the most transformative parts of our district’s math journey.

Results we can see

In the past five years, Charleston County’s math scores have climbed roughly 10 percentage points. But the most meaningful growth is happening inside classrooms:

• Students are reasoning more deeply.
• Teachers demonstrate stronger content knowledge and efficacy in using math models.
• PLC conversations focus on evidence of student thinking.
• Instruction is more intentional and responsive.

Teachers are also the first to tell you whether PD is worth their time…and our teachers are asking for more. Many return to complete a second or third strand, and sometimes all four. We even have educators take the same strand more than once just to pick up on something they may have missed the first time. The desire to deepen their expertise shows just how impactful this learning has been. Participants also find it powerful to engage in a room where the collective experience spans multiple grade levels. This structure supports our goal of strengthening vertical alignment across the district.

Prioritizing professional learning that works

When professional learning builds teacher expertise rather than compliance, everything changes. This approach doesn’t tell teachers what to teach; it helps them understand how students learn.

And once teachers gain that insight, classrooms shift. Conversations deepen. Confidence grows. Students stop memorizing math and start truly understanding it.