Research

Contrast work.

Discover the gap.

The Contrast routine is grounded in peer-reviewed research from Harvard and Vanderbilt. Side-by-side comparison is among the best-supported instructional strategies in learning science.

The KPop Demon Hunters defeated 17 demons this week.They gained 24 new fans for each demon defeated.How many new fans in all?Student A17 × 247 × 20 = 1407 × 4 = 2810 × 20 = 20010 × 4 = 40140 + 28 + 200 + 40= 408408 new fansStudent B17 × 247 × 20 = 1407 × 4 = 281 × 20 = 201 × 4 = 4140 + 28 + 20 + 4= 192192 new fans

Can you spot where one went wrong?

The Core Idea

Comparison beats explanation

Show students two responses side by side. They figure out what’s the same, what’s different and why it matters.

This activates a deep cognitive process. Comparison forces students to notice features they would otherwise overlook.

Researchers call it “contrasting cases.” Twenty years of studies confirm it works across subjects and grade levels — which is why it’s already embedded in leading curricula, teacher training programs, and the classrooms of the highest-performing schools in the country.

What the Research Shows

Six findings. Two decades of evidence.

1
Comparison beats sequential study
Students who compare two solutions outperform those who study them one at a time.
2
What you compare matters
The type of pairing determines the type of learning — correct vs. incorrect builds conceptual understanding; two correct methods builds flexible thinking.
3
Incorrect examples deepen understanding
Analyzing errors builds the conceptual structure that prevents future mistakes.
4
Prior knowledge amplifies the effect
Students who attempt a problem first gain more from the comparison that follows.
5
Federal endorsement: IES Practice Guide, 2012
The Institute of Education Sciences recommends comparison as a core math teaching strategy.
6
The implementation gap is the opportunity
Most teachers know comparison works. Few have time to analyze classwork and build the materials daily.
The Classroom Routine

The Contrast Routine in 10 minutes.

A structured sequence any teacher can run. Minimal prep. Maximum impact.

Project
Display two student responses side by side on the projector.
Commit
Students silently choose which response is correct and why.
Turn and talk
Pairs discuss their reasoning before the whole-class conversation.
Stamp the takeaway
After students identify the difference, name the underlying idea.
Practice
Students apply the takeaway with a fresh problem.
Published Research

Peer-reviewed. Replicated. Trusted.

Rittle-Johnson, B., & Star, J. R. (2007). Does comparing solution methods facilitate conceptual and procedural knowledge? An experimental study on learning to solve equations. Journal of Educational Psychology, 99(3), 561-574.

Students assigned to compare methods gained more flexibility and conceptual knowledge than those who studied methods sequentially.

Rittle-Johnson, B., Star, J. R., & Durkin, K. (2009). The importance of prior knowledge when comparing examples: Influences on conceptual and procedural knowledge of equation solving. Journal of Educational Psychology, 101(4), 836–852.

Prompting “what’s the same?” before “what’s different?” produces stronger learning by grounding comparison in shared structure.

Star, J. R., & Rittle-Johnson, B. (2009). It pays to compare: An experimental study on computational estimation. Journal of Experimental Child Psychology, 102(4), 408-426.

The comparison advantage extends to estimation tasks across grade levels.

Schwartz, D. L., & Bransford, J. D. (1998). A time for telling. Cognition and Instruction, 16(4), 475-522.

Experiencing contrasting cases before instruction primes students to understand subsequent explanations.

Why this outperforms traditional review

Traditional review shows the right answer and asks students to copy it. Contrast shows two paths and asks students to reason about the difference.

That cognitive effort is the learning. The comparison itself is the instruction.

See the research in action

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