The Gold Standard.
Randomized. Rigorous.
The Strongest Claim in K–12 Research.
ESSA Tier I (Strong Evidence) is earned through a randomized controlled trial — the study design that allows the most definitive claim in education research: your product caused the learning gains. It requires the most preparation and the most discipline, and it produces the most durable, defensible evidence base an edtech company can hold.
Strong Evidence.
The claim no other design can make.
A Tier I approval on the Evidence for ESSA list signals something that no retrospective study, no cohort comparison, and no quasi-experimental design can claim: that random assignment separated who got the product from who didn’t, and students in treatment still learned significantly more. That’s a different kind of evidence — and it’s treated differently by state evaluators, district procurement panels, and What Works Clearinghouse reviewers.
Highest ESSA Evidence Tier
Tier I is the ceiling. No other study design produces a higher ESSA evidence rating.
What Works Clearinghouse Eligible
RCT designs meet the standards required for What Works Clearinghouse review — the federal government’s benchmark for education evidence.
Durable Competitive Advantage
A Tier I approval is rare in edtech and difficult to replicate. It distinguishes your product in state approval processes and district procurement for years.
What Makes a Randomized Controlled Trial Different
In a quasi-experimental study (the design used for Tier II), a researcher looks for comparison schools that are as similar as possible to the schools using your product — same demographics, similar prior achievement, ideally the same district. It’s rigorous, and when done well, the evidence is meaningful. But the comparison group was not formed randomly. That matters, because some unmeasured difference between the groups could explain the results.
A randomized controlled trial removes that possibility. Schools, classrooms, or students are randomly assigned to the treatment or control condition before the study begins. Random assignment means there’s no systematic way for the groups to differ at the outset — and that means any difference in outcomes at the end can be attributed to the intervention with a level of confidence no other design can match.
In practice, randomization in schools works at the classroom or school level — teachers or schools agree to participate, and assignment to treatment or comparison is determined by a random process. No student is denied access to a product permanently; in many designs, comparison schools receive access after the study period ends. The logistical complexity is real, but it’s manageable with the right research partner and district relationships.
How Randomization Works
Randomized controlled trials assign participants to conditions before the study begins — so any pre-existing differences between groups are distributed by chance, not by selection. This is what makes the causal claim possible.
Participating Schools / Classrooms
All participants agree to the study; assignment to condition is determined randomly.
Treatment Group
Implements your product during the study period. Pre- and post-assessment collected at the same time points as control.
Control Group
Continues with existing instruction. Same assessments, same calendar. Often receives access to the product after the study concludes.
Because assignment was random, any difference in outcomes is attributable to the intervention — not to pre-existing differences between groups. This is what ESSA Tier I Strong Evidence certifies.
Tier I Is the Goal. It Requires the Right Foundation.
An RCT is the logical next step for companies that have already built an evidence base — typically through one or more Tier II or Tier III studies — and are ready to pursue the highest possible rating. The logistical requirements are real: districts must agree to random assignment, the sample size needed to achieve statistical power is generally larger than for a quasi-experimental study, and the study must be designed entirely before implementation begins.
Companies that pursue Tier I well tend to share a few characteristics: they have existing relationships with districts that already trust and value their product, they have a research partner who has navigated randomized designs in school settings before, and they understand that a Tier I study is a multi-year investment in their evidence base — not a credential to check quickly.
Not ready for Tier I yet? A Real-Time Tier II study (quasi-experimental) is the strongest pathway available outside of randomization, and in many markets it’s what procurement committees are specifically looking for. Michigan, Arizona, and several other states weight Tier I and Tier II evidence similarly in scoring rubrics — and a Tier II study can be completed in a single school year. Many of our clients build toward Tier I through an initial Tier II engagement.
Research Rigor and Implementation Support Are Not in Tension
The most common concern about RCTs in school settings is that they feel extractive — researchers collect data without providing anything back to the schools bearing the burden of participation. Our approach is different. Because we are engaged with treatment schools throughout the study year, we actively support administrators in implementing your product with fidelity — which protects study integrity and produces better outcomes for students at the same time.
Administrator Interviews and Coaching
Structured midpoint check-ins identify implementation challenges before they affect study quality. Administrators receive actionable guidance, not just data collection requests.
Fidelity Monitoring
We track implementation quality throughout the school year. Schools that implement with integrity produce cleaner, stronger results — and better evidence for your company’s buyers.
District Relationship Continuity
Schools that participated in a successful RCT often become long-term partners — advocates, case study subjects, and references for future sales conversations.
Equitable Study Design
We design studies so that control schools receive access to your product after the study period when possible — ensuring that participation in research does not disadvantage students or teachers.
Study Deliverables
Every Real-Time ESSA Tier I Study includes a complete package — from randomization protocol through What Works Clearinghouse-aligned publication.
Pre-Registered Study Design and Randomization Protocol
Evidence for ESSA and What Works Clearinghouse require that Tier I studies be designed and randomization procedures documented before implementation begins. We develop the full protocol — including power analysis, randomization procedure, analysis plan, and assessment schedule — before a single school year begins.
District Recruitment and Random Assignment
We identify and recruit participating schools, manage data sharing agreements, and implement the randomization procedure to assign schools or classrooms to treatment and control conditions. The randomization process is documented and transparent for reviewer scrutiny.
Administrator and Literacy Coach Interviews — Both Groups
We conduct structured interviews with administrators and instructional coaches in both treatment and control schools throughout the school year. Treatment interviews capture implementation quality, fidelity, and how teachers are adapting to the program. Control school interviews document what comparison schools are actually doing instead — which curriculum, how much time on task, what supplemental programs are in use. This symmetry is what allows the study to answer not just “did treatment students gain more?” but “gain more than what?” — which is exactly what a sophisticated reviewer or district buyer will ask.
Educator Surveys — Treatment and Control Schools
Teachers in both conditions complete surveys that capture instructional context, perceived student progress, and professional development experience. Fall surveys collect control school baseline data on how comparison teachers teach the relevant skills; spring surveys capture treatment teacher experience with the product. The combined dataset lets you show not just that your teachers felt the product worked — but that treatment teachers were using measurably different instructional approaches than their peers in control schools.
Intent-to-Treat and Per-Protocol Analysis
Rigorous statistical analysis following best practices for RCTs — including intent-to-treat analysis, attrition documentation, effect size calculation, significance testing, and subgroup analysis. Designed to meet What Works Clearinghouse and Evidence for ESSA Tier I standards.
Academic Research Report
A peer-review-ready report with full methodology, results, discussion, and limitations — written to the standards of Evidence for ESSA, What Works Clearinghouse, and state-level review bodies.
Research Summary (Co-Branded)
An educator-friendly executive summary for your sales team — distilling the study’s key findings in a format designed for district buyers, conference presentations, and RFP attachments.
Evidence for ESSA, What Works Clearinghouse, and Certification Submission
LXD Research manages submission to Evidence for ESSA (Johns Hopkins), EduEvidence, and Digital Promise, and can support What Works Clearinghouse submission preparation — so your study arrives certified and indexed without additional coordination on your part.
How a Tier I Study Unfolds
A Tier I study requires more lead time than a quasi-experimental design, primarily because randomization and pre-registration must occur before the school year begins. The full engagement typically spans 12–24 months depending on sample size, district availability, and assessment timing.
Feasibility Assessment, Study Design, and Power Analysis
We assess whether your implementation context, existing district relationships, and available sample size can support a credible RCT. Power analysis determines the number of classrooms or schools needed. The full study design — including randomization procedure and analysis plan — is finalized and documented before recruitment begins.
District Recruitment, Consent, and Random Assignment
We identify participating schools, confirm enrollment and prior achievement data for power calculations, execute data sharing agreements, and implement random assignment. Schools receive clear communication about what participation entails — and what control schools will receive after the study concludes.
Data Collection, Interviews, and Implementation Support
Pre-assessments collected at study start. Throughout the school year, administrator interviews and implementation monitoring support fidelity in treatment schools. Post-assessments collected at year’s end. Attrition and participation are tracked throughout.
Intent-to-Treat Analysis, Effect Sizes, and Report Drafting
Full RCT analysis following What Works Clearinghouse-aligned procedures — including intent-to-treat analysis, attrition documentation, and subgroup breakdowns. Draft report delivered for review.
Report Delivery, Publication, and Certification Submission
Finalized reports are published to ERIC and ResearchGate, submitted to Evidence for ESSA and EduEvidence for certification review, and prepared for What Works Clearinghouse submission where applicable.
What a Real ESSA Tier I Study Looks Like
This is an LXD Research randomized controlled trial that earned ESSA Tier I (Strong Evidence) approval on the Evidence for ESSA national list.
95 Percent Group — 95 Phonics Core Program Efficacy Study, 2021–22
95 Percent Group wanted the strongest possible evidence for their flagship phonics curriculum — not a quasi-experimental comparison, but a true randomized trial. LXD Research recruited a Missouri district with 14 elementary schools, organized the schools into matched pairs by size and prior ELA scores, then used a coin toss to assign one school in each pair to the 95 Phonics Core Program and the other to continue with the district’s existing ReadyGEN curriculum. That randomization — designed before the school year began — is what qualifies the study for ESSA Tier I.
The study covered 3,569 students in grades K–2, with pre-, mid-, and end-of-year Acadience Reading assessments at all three time points. Qualitative work ran symmetrically across both conditions: fall surveys of control teachers documented how comparison schools taught phonics; spring surveys captured treatment teacher experience and comfort with the program. Literacy coach interviews were conducted in both treatment and control schools — seven treatment coaches, eight comparison coaches — along with classroom observations across all grades in both groups. The result is a study that doesn’t just show treatment students gained more; it shows exactly what control students were doing instead, and why the difference matters.
Treatment students gained significantly more than control in composite scores — with the largest gains among students who started the year below benchmark.
Significant treatment effect on Nonsense Word Fluency Correct Letter Sounds — a core phonics decoding measure — with treatment students demonstrating meaningfully stronger growth.
Significant treatment effects on composite scores, oral reading fluency, and ORF accuracy — with the strongest gains among students who were already at or above benchmark at the start of the year.
Attrition was only 4% and was statistically equivalent between treatment and control groups — a key Evidence for ESSA requirement. Baseline equivalence was confirmed at all three grade levels before analysis began.
The firm that has produced more ESSA-approved studies than any other independent research organization.
The most important thing an edtech company can do before investing in a Tier I study is choose a research partner who has navigated Evidence for ESSA review, managed the complexity of school-based randomization, and maintained district relationships through the full length of a real-time study. LXD Research has done all three — and we work exclusively with edtech companies, which means we understand the market realities that academic research firms often don’t. Our studies are designed to pass methodological review and to work for your buyers.
A Tier I RCT is the right goal for companies with a strong existing evidence base and established district partnerships. If you’re earlier in your research journey, a Real-Time Tier II Study (quasi-experimental, concurrent comparison group) is the most rigorous non-randomized design available — and it’s what the majority of state procurement processes specifically require. Many clients build toward Tier I through an initial Tier II engagement.
← Learn about Real-Time Tier II StudiesThe researcher who has navigated more ESSA approvals than any other independent firm.
Dr. Rachel Schechter founded LXD Research after serving as Director of Research at Lexia Learning, where she built a 12-member research department and a portfolio of What Works Clearinghouse-aligned studies. LXD Research has produced more studies approved by Johns Hopkins’ Evidence for ESSA than any other independent research organization.
Her background spans randomized and quasi-experimental designs across literacy, math, professional development, and formative assessment. She understands what it takes to design studies that survive rigorous reviewer scrutiny — and to build the district relationships required to run them well.
Is your evidence base
ready for Tier I?
Schedule a free consultation to assess whether your implementation context, district relationships, and sample size can support a credible randomized controlled trial — and what the realistic timeline and investment look like.