For K-2 Teachers · DMT Insight

One puzzle:
every operation, the Diamond Problem teaches thinking, not steps.

Free to read in full, no gate. And it comes from Math Success: a complete, teacher-friendly, conceptual-first math program with the greatest prep and support teachers have ever experienced, for $21 a month.

Free insight 5-minute read · teaching video included

The Diamond Problem

Common shape posters and worksheets create misconceptions, "diamond" among them. This insight shows how teaching shapes as intersecting lines and invariant properties builds real geometric reasoning, and why the Diamond Problem routine carries that reasoning from kindergarten compose and decompose all the way to Grade 5 factors.

A student reasoning on a number line
Number-line reasoning, mid-puzzle
35%+
avg. test score increase
300+
schools transformed
40+ yrs
of classroom research

What this insight covers

The three ideas that do the heavy lifting. The full article goes deeper, free, no gate.

1

One routine, every operation

The same diamond shape works for addition, subtraction, multiplication, and division, students see how the operations are related, not four separate procedures.

2

Thinking before the answer

The empty cell forces the question "what do I know, and what does it tell me?", reasoning first, computation second.

3

It scales with the child

Kindergarteners compose and decompose with it. Fifth graders use it for fractions and factors. Same puzzle, deeper numbers.

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From real classrooms, on tape

Teachers who watched understanding arrive, and said so.

“I saw light bulbs turn on and thinking turn on that I had never seen with math.”

ANGELA WILLIAMS · TEACHER

“This is it. This is how to teach math.”

MOLLY YORK · TEACHER

“These kids aren't just saying math words anymore. They can explain them and show models to back it up.” Rosie Ashcraft. Ms. Hochstrasser's 4th graders made dramatic gains, the kind you can point to on the assessments and see in how students talk about the math.

Start with the Diamond Problem insight, free

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The full insight

The Diamond Problem, the article, with the research and the classroom takeaways.

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The Diamond Problem, DMT Insight teaching video still
DMT INSIGHT · The Diamond Problem

The teaching video

Watch the lesson taught, models, questions, and the language, on tape.

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Try it with students

The activities and demo lesson that go with this idea, open now.

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A DMTI math specialist teaching an open number line lesson, students' hands up, everyone in Coach in the room, number line up
Dr. Jackie Ismail and Dr. Jonathan Brendefur coaching Natalie over Zoom, the real weekly virtual session Real coaching, live over Zoom
Dr. Sam Strother teaching fractions at the board Stuck on a lesson? He's got answers.
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3

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Dr. Jonathan Brendefur
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Tell us about one student who's stuck, or one lesson that keeps falling flat, and we'll help you build the plan for it. That's the partnership: teacher-led, expert-backed. We don't push a system downward; we listen, advise, question, and support.

Dr. Jonathan Brendefur, founder, DMTI

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P.S., for the skippers

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The K-2 Pack, free on this page: the K-2 demo lesson, Math Fact Fluency, The Diamond Problem, plus free practice activities, yours either way.
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