Vocabulary assessment: measuring vocabulary growth for IEP goals

By the IEP Atlas editorial teamLast updated November 1, 2026

Short answer

To measure vocabulary growth for an IEP goal, define the word set, pick a format that matches what the goal asks (pointing, explaining, answering questions or using the word), build equal probe forms, score with a fixed 0 to 2 rule, take 3 baseline probes, then probe weekly or biweekly. Standardized tests describe the gap; probes track growth.

Vocabulary is easy to teach badly and easy to measure badly. A matching quiz on Friday tells you the student remembered Monday's definitions. It does not tell you whether the student understands the word in a new sentence, uses it in class or remembers it in March. Good vocabulary assessment for an IEP goal checks the kind of knowing the goal is about, the same way every time.

The steps below each come with an example, and the worked example follows one fictional 3rd grader on an SLP caseload. Numbers are illustrations. For the broader comprehension context, see the cluster pillar on reading comprehension strategies.

Two jobs, two kinds of tools

Job	Tool	What it tells you	How often
Describe the gap	Standardized receptive and expressive vocabulary tests	How the student compares with same-age peers	At evaluation and reevaluation
Track growth	Short curriculum-based probes on taught or target words	Whether the student is learning the words you teach	Weekly or every 2 weeks
Check transfer	Word use in class work and writing samples	Whether the words show up outside therapy	Monthly or each grading period

Standardized scores move slowly and are not built for weekly decisions. Progress monitoring relies on short, repeated measures given the same way over time.^[1] The IEP must say how progress on each goal will be measured and reported.^[2]

What you need before you start

The word set. A defined list: this unit's 10 words, or a pool of 40 taught words sampled each week.
A format that matches the goal. See Step 2.
Unfamiliar sentences or contexts for each word, different from the teaching sentences.
A scoring rule written down before the first probe.

Step-by-step vocabulary measurement

Step 1: Define the word set

Pick one of two designs. A unit set tests the same 8 to 12 words each week of a unit. It shows learning fast but restarts every unit. A cumulative pool samples 10 words a week from all words taught so far. It shows retention and gives a smoother year-long graph. For most IEP goals, the cumulative pool is the better choice.

Step 2: Match the format to the goal

Goal asks the student to	Format	Example item
Recognize the word	Point to the picture from 3 or 4	"Show me cautious."
Understand the meaning	Yes, no or choice question	"Would a cautious person run on ice?"
Explain the word	Define or give an example	"What does cautious mean? Give an example."
Use the word	Sentence or written response	"Use cautious in a sentence about the playground."
Figure out new words	Unfamiliar word in context	Read a passage, explain a new word using clues or parts

Receptive formats are easier and often fit younger students or AAC users. Expressive formats fit goals about explaining and using words. Do not switch formats mid-year, or the graph will show the format change instead of learning.

Step 3: Build equal probe forms

Write items in new sentences the student has not practiced. Keep them similar in length and difficulty across forms. For a cumulative pool, randomly draw 10 words each week.

Step 4: Fix the scoring rule

A 0 to 2 rule works for explanations:

2: correct meaning in the student's own words, or a correct example that shows the meaning.
1: partly correct, a related word, or a correct example with no explanation.
0: incorrect, no response, or the word repeated.

Write 2 or 3 sample answers for each score before you begin. If two staff members score probes, have both score the same 3 probes and compare.

Step 5: Take 3 baseline probes

Probe on 3 different days before teaching begins and report the median. Baselines on taught-word goals are often near zero, which is fine.

Step 6: Probe on a schedule and graph it

Probe weekly for unit sets and every 2 weeks for cumulative pools. Graph the total, out of 20 for 10 words at 2 points each. Decide in advance what a flat line means, such as 4 probes below the aim line.

Worked example: one student across 12 weeks

Student (fictional): Jada, grade 3, language disorder, on the SLP's caseload for 2 sessions of 30 minutes a week. Standardized testing in September placed her receptive and expressive vocabulary well below age expectations.

Word set. A cumulative pool of curriculum words taught in therapy and class, 4 new words a week. Each probe draws 10 words from the pool.

Format. Explain the word or give an example, scored 0 to 2. Total out of 20.

Baseline, October 1 to 10. Before teaching, on 10 words sampled from the first 3 weeks of planned words: 2, 4 and 3 of 20. Median 3 of 20.

Goal. Given 10 words sampled from taught curriculum vocabulary, presented in unfamiliar sentences, Jada will explain each word or give an example that shows its meaning, scoring at least 15 of 20 points on 3 consecutive biweekly probes. See the template to explain pre-taught unit words before the lesson and the vocabulary semantics goals.

Probe date	Words in pool	Score (of 20)	Words at 2 points (of 10)
Oct 10 (baseline median)	0 taught	3	0
Oct 24	8	7	2
Nov 7	16	9	3
Nov 21	24	11	4
Dec 5	32	12	5
Dec 19	40	14	6
Jan 9	48	15	7

The slope is steady, about 2 points every 2 weeks. The December dip in speed reflects a growing pool: harder to remember 40 words than 8. That is why a cumulative pool is a tougher, more honest test.

Transfer check, December. The SLP and teacher looked at a science writing sample. Jada used 3 taught words correctly, up from 0 in September.

Common mistakes

Weak: Testing with the same sentences used in teaching. Better: Use new sentences so the probe shows understanding, not memory of the lesson.
Weak: Reporting a standardized vocabulary score as the progress measure. Better: Use short probes for progress and save standardized tests for evaluations.
Weak: Changing from pointing to explaining in January. Better: Keep one format all year; add a second goal if the target changes.
Weak: Scoring "close enough" by feel. Better: Write the 0 to 2 rule with sample answers before the first probe.
Weak: A goal that says "will increase vocabulary." Better: Name the word set, the format, the score and the schedule, as in Jada's goal.

Record probes on a rubric scoring data sheet for 0 to 2 scoring or an accuracy data sheet for right or wrong items. Rubric scoring explains point scales. For teaching the words, see vocabulary interventions and explicit vocabulary instruction; for how depth of knowledge changes what you test, see levels of word knowledge. The SLP goal view is in vocabulary goals for speech therapy, and more wording is on the vocabulary goals page. Paste a draft into the goal checker to confirm it is measurable.

Frequently asked questions

How do you measure vocabulary growth?

Use short probes on a defined set of words, in a format that matches the goal, scored the same way every time. Take 3 baseline probes, then probe weekly or every 2 weeks and graph the scores. Check use in class work each grading period.

Should I use a standardized test to track vocabulary progress?

Standardized tests are built to compare a student with peers and change slowly. They are useful at evaluation time. For progress on an IEP goal, short probes on the words you teach show change much sooner.

Receptive or expressive vocabulary probes: which should I use?

Match the goal. If the goal is about understanding, use pointing or yes and no questions. If it is about explaining or using words, use expressive probes. Keep the same format all year so the graph is fair.

Use it in IEP Atlas

Sources

Progress Monitoring: Data & Goal Setting, National Center on Intensive Intervention
34 CFR §300.320: Definition of individualized education program, Legal Information Institute, Cornell Law School

Written and checked by the IEP Atlas editorial team under our editorial policy. This guide describes general practice and federal rules. It is not legal advice; your state may add requirements, and the IEP team makes the decisions for each student.