What Is Specially Designed Instruction (SDI)? A Plain-Language Guide for Teachers

If you have ever stared at the SDI box on an IEP and thought "wait, how is this different from the accommodations I just wrote?", you are in good company. This is a plain-language guide for special-education teachers and case managers who want to write SDI that actually means something and survives a second read. This was the section I struggled with most as a classroom teacher, mostly because nobody ever showed me the difference in plain terms, so that is where I am starting here.

What SDI actually is

Specially designed instruction is the part of the IEP where you describe how you will change what you teach, how you teach it, or the way you measure it so the student can make progress toward their goals. It is the instructional heart of special education. If the goals say where the student is headed, SDI says how you, the teacher, will get them there.

Here is the simplest test. SDI is the teaching that is different for this student because of their disability. Not different seating, not extra time. Different instruction. A student who needs explicit, systematic phonics instruction in a small group, with cumulative review and immediate corrective feedback, is receiving SDI. The content, methodology, and delivery have been adapted to their need.

A quick honest note before we go further. This article is general information about writing IEPs, not legal advice. IDEA sets the broad expectations, but how SDI is documented and delivered varies by state and district, so lean on your team and your local guidance for anything compliance-related.

SDI vs. accommodations: the difference that trips everyone up

This is the confusion worth clearing up. An accommodation changes the conditions around the task so a student can show what they know without changing the skill being taught or tested. SDI changes the instruction itself.

Think of it this way. An accommodation removes a barrier. SDI builds a skill.

• A student gets extended time on a math test. That is an accommodation. The math has not changed, only the clock.
• The same student receives direct instruction in a sequenced set of problem-solving steps, with the teacher modeling, then practicing with the student, then fading support. That is SDI. You are teaching the math differently.

A fast gut-check question: "If I gave this support to every kid in a general education class, would it still make sense?" Extended time, preferred seating, and a quiet space usually would. Explicit instruction in decoding multisyllabic words, delivered in a structured small group, would not. That second one is specially designed.

The components of strong SDI

Good SDI is not a single sentence naming a program. It usually answers four questions in plain terms.

1. Content. What is being taught or adapted? For example, a reduced set of essential vocabulary, or pre-taught background knowledge.
2. Methodology. What instructional approach will you use? Explicit instruction, modeling, guided practice, error correction, chunking, graphic organizers.
3. Delivery. How and where? Small group, one-to-one, frequency, who provides it.
4. Why it matches the need. The thread back to the student's disability and goals.

A common red flag is SDI that names a curriculum and stops there. A program name is not instruction. The team should be able to picture what the teaching looks like on a Tuesday.

A weak SDI example, then an improved one

Here is realistic SDI for a student who struggles with written expression.

Weaker version:

Student will receive specially designed instruction in writing using a research-based program.

Read that back. It names a category and a vague endorsement, but nobody knows what you will do. A substitute could not deliver it. A parent cannot picture it.

Improved version:

Teacher will provide explicit, small-group instruction (group of 3 or fewer) in paragraph writing 4 times per week for 30 minutes. Instruction will use a model-then-guided-practice sequence: the teacher models composing a topic sentence and two supporting details using a sentence-starter framework, then students practice with teacher feedback before writing independently. Visual organizers and a checklist will be faded as the student demonstrates accuracy.

Now the content, methodology, and delivery are all visible, and the support has a built-in plan to fade. That is the difference between a label and a description.

More SDI examples across different needs

SDI looks different across needs. Some realistic snippets:

• Math computation. "Direct instruction in a step-by-step strategy for multi-digit subtraction with regrouping, using concrete manipulatives, then drawings, then numbers only, with daily cumulative review."
• Behavior and self-regulation. "Explicit instruction and rehearsal of a self-monitoring routine, where the student is taught to check a short task list and rate their own focus, with teacher modeling and gradually faded prompts."
• Receptive language. "Pre-teaching of key vocabulary before each science unit, using visuals and repeated, structured exposure, so the student enters the lesson with the terms already introduced."

Notice none of these mention extended time or a quiet room. Those would belong in the accommodations section, not here.

A quick pre-flight checklist for your SDI

Before you call the SDI section done, run through these:

• Does it describe instruction, not just conditions or settings?
• Can a reader picture the teaching, including the methodology and how support fades?
• Is the frequency, duration, group size, and provider clear?
• Does it connect back to the student's goals and area of need?
• Did anything sneak in that is really an accommodation? Move it.
• Is it free of vague phrases like "as needed" or a bare program name with no description?

If you want a second set of eyes on a draft before the meeting, IEP Pre-Flight lets you paste your SDI language and get structured feedback on what reads as vague, missing, or unmeasurable, plus suggested revisions.

Write SDI the way you would explain it to a colleague covering your class: here is what I teach this student that is different, here is how I teach it, and here is how I will know it is working. Get that on the page and your SDI section will do its real job.