MTSS and RTI: what tiers of support are, how to run them, and what the research says

What it is

MTSS (multi-tiered system of supports) and RTI (response to intervention) are two names for the same basic design, with MTSS the broader one. The idea is that a school doesn't wait for a student to fail before helping. Instead, it checks every student, notices who is falling behind early, and gives extra teaching in layers.

• Tier 1: good teaching for everyone in the general classroom, using a strong core curriculum.
• Tier 2: extra small-group teaching, usually several times a week, for students who score below a benchmark on a screening test.
• Tier 3: more intensive, often daily or one-to-one, help for students who don't respond to tier 2. Some of these students are evaluated for special education.

Two routines hold the system together. Universal screening gives every student a short test, usually two or three times a year, to find who might be at risk. Progress monitoring checks students in tiers 2 and 3 more often to see whether the extra help is working, and moves them up, down or out of the tiers.

RTI is most often used for reading, and in many schools it is part of how learning disabilities are identified. MTSS widens it to math, behavior and social-emotional support. On the behavior side, a widely used tiered model is schoolwide positive behavioral interventions and supports (PBIS): clear expectations taught to everyone, extra support for some, and intensive plans for a few.

Why it works

The logic is sound: catch difficulties early, when they're smaller, and match the intensity of help to the need. A student who's a little behind in decoding in October can often catch up with a few weeks of focused small-group teaching; the same student found in third grade has more to make up.

The parts that have been tested on their own have good evidence. The What Works Clearinghouse practice guide on tiered reading support, from a panel chaired by Russell Gersten, rates intensive, systematic small-group instruction on up to three foundational skills as Strong. Jeanne Wanzek and colleagues' meta-analysis of 72 studies found that tier 2 type reading interventions for students in kindergarten to third grade improved foundational reading skills, and to a lesser extent language and comprehension. In math, the Clearinghouse's 2021 intervention guide rates systematic instruction during intervention as Strong. On behavior, Catherine Bradshaw and colleagues' five-year randomized trial in 37 elementary schools found schoolwide PBIS cut suspensions and office discipline referrals.

The system as a whole is a different matter. In 2015 the federal government's evaluation, led by Rekha Balu, looked at 146 schools in 13 states that were experienced with RTI. Using each school's screening cutoff, it compared students just below the line (who got intervention) with students just above it (who didn't). In first grade, the students who got intervention ended the year with lower reading scores. In second and third grade, there was no significant difference.

That doesn't mean intervention doesn't work. The study measured the effect for students close to the cutoff, in schools as they ran RTI in 2011–12. The report also found that many schools gave intervention to first graders who were already reading at or above grade level. The report doesn't settle why intervention didn't help near the cutoff; the practical lesson for schools is about quality, since an intervention group is only as good as the teaching in it and the time it doesn't take away.

How to start, by grade

Examples

• A tier 2 decoding groupGrades 1–2

  Five first graders who scored below the winter benchmark on a nonsense-word fluency screener meet with a reading specialist for thirty minutes, four days a week. Each lesson: review of known letter sounds, explicit teaching of one new pattern, blending and spelling practice, and reading decodable sentences. A one-minute probe every two weeks shows who's catching up.

• Grade-level data meetingGrades K–5

  Every six weeks the second-grade team looks at progress graphs for students in tiers 2 and 3. Two students have met their goals and return to tier 1 with a check in a month. One hasn't moved, so the team changes the intervention, increases the time and asks the reading specialist to observe a session.

• Math intervention blockGrades 3–5

  A thirty-minute block four days a week when no new core content is taught. Students below benchmark in fractions work with a teacher using fraction bars and the number line; the rest do enrichment or practice. Groups change every unit based on a short check.

• Schoolwide behavior expectationsAll grades

  Three expectations (be safe, be respectful, be responsible) are taught explicitly in the first weeks and revisited after breaks, with examples for each place in school. Staff acknowledge students who meet them. A small group of students with repeated referrals check in with an adult each morning and afternoon.

• Intervention period in middle schoolGrades 6–8

  A forty-minute period built into the timetable. Students identified by screening and grades go to small-group reading or math intervention; others choose study hall, enrichment or clubs. Nobody misses science or social studies to get help.

Common mistakes

Pulling students out of core instruction for intervention.

If tier 2 replaces tier 1 instead of adding to it, the student gets less good teaching, not more. Schedule intervention in its own time.

Weak interventions.

Worksheets with an assistant, or computer time without teaching, isn't what the research tested. Use interventions with evidence, delivered explicitly and systematically by trained staff.

Groups by overall score instead of skill.

Two students with the same low reading score may need completely different help. Follow screening with a quick diagnostic and group by the skill that's missing.

Data that change nothing.

Progress monitoring is only useful if someone looks at it and acts. Set dates for team meetings and clear rules for moving students.

Using the tiers as a reason to wait.

Tiers are for getting help to students sooner, not later. If a disability is suspected or a parent asks about an evaluation, talk to your special education team about the next step rather than waiting for more data.

Neglecting tier 1.

If a third of a class needs tier 2, the problem is usually the core curriculum or instruction, not the students. Fix tier 1 first; the tiers can't make up for it.

Time and cost

Time: screening takes a few minutes per student two or three times a year; tier 2 groups typically meet three to five times a week; team data meetings every few weeks.

Money and staff: the real cost. Interventions need trained people (specialists, teachers, well-trained assistants), validated screeners and intervention programs, and time in the timetable.

Training: substantial. Staff need to give screeners consistently, read the data, deliver interventions as designed and make decisions together. Expect it to take more than a year to run well.

Debates and open questions

Why did the federal evaluation find no benefit? Its authors studied students near the cutoff, not those far below it, and reported that many schools gave intervention to students already reading at grade level. The summary we read doesn't settle the reason. Questions worth asking about your own school: does intervention time replace core instruction, and are the interventions as intensive and explicit as the ones the research tested? The study is a warning about implementation, not proof that small-group help fails.

Screening accuracy. Short screeners miss some students who need help and flag some who don't. Using more than one measure, and checking with a diagnostic, reduces mistakes.

How much does progress monitoring add? The Clearinghouse panel rated monthly progress monitoring in tier 2 as Minimal evidence: sensible, widely used, but not tested rigorously on its own. It's worth doing, but the intervention itself is what moves achievement.

PBIS outcomes. The Bradshaw trial measured suspensions and office referrals, which fell; the same study also looked at academic achievement, and the summary we read reports the behavior results. We'll add academic findings when we've confirmed them at the source.

Tools that do it

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• Reading fluency timer and WCPM calculator: one-minute oral reading probes for screening and progress monitoring.
• Decodable sentences by phonics pattern: practice text for tier 2 decoding groups, matched to the pattern taught.
• Math fact fluency: short timed practice; the math intervention guide rates timed activities Strong.
• Fraction bars: concrete representations for small-group math intervention.
• Random group maker: quick grouping when you rotate the rest of the class while you teach a small group.
• Centers rotation board: run independent rotations on the projector while you work with a tier 2 group.
• Behavior point chart: a simple daily chart for students on a check-in plan.

Questions teachers ask

What's the difference between MTSS and RTI?

RTI usually means tiered support for academics, especially reading, and is often tied to identifying learning disabilities. MTSS is the broader framework that includes academics, behavior and social-emotional support under one system. In practice many schools use the names interchangeably.

Does RTI work?

The interventions do, when they're systematic, explicit and well taught: the What Works Clearinghouse rates small-group foundational skills instruction Strong, and a meta-analysis of 72 studies found tier 2 type reading interventions helped. The large federal evaluation of RTI as schools ran it found no benefit near the cutoff and a negative effect in first grade, which points to implementation.

How often should we screen?

The reading RTI practice guide recommends screening all students at the beginning and middle of the year, and rates that recommendation Moderate. Many schools add a spring screening to check the year's progress.

How long should a student stay in tier 2?

Long enough to judge whether it's working, which in most decision rules means several weeks of data points. Set the rule in advance, check the data at team meetings, and change the intervention if the student isn't progressing rather than waiting a whole year.

Is PBIS part of MTSS?

Yes, usually as the behavior strand: schoolwide expectations taught to everyone, extra support for some students, and intensive plans for a few. A randomized trial in 37 elementary schools found it reduced suspensions and office referrals.

Does a student have to go through every tier before a special education evaluation?

Tiers are meant to get help to students sooner, not to make them wait. If a disability is suspected, or a parent asks about an evaluation, raise it with your special education team straight away; your district's special education office can tell you the rules that apply.