Teaching · Speech & Language

Mark the morphemes.
The page counts.

Paste a language sample, one utterance per line. The page counts as you type, leaves out mazes and unintelligible utterances, and reports MLU, total words, different words and the type-token ratio with every utterance in view.

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Included with Caveat Classroom and Whole-school licenses. Or get it in the Speech & Language toolkit, $79 for 72 items.

The language sample calculator

The worked example is a made-up play sample from a child aged 3;2: 55 utterances, 52 of them counted. Type over it, or start blank.

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What you get

Teaching · Speech & Language$12 · included with Classroom and Whole-school licenses

What you finish with: Mean length of utterance in morphemes and in words; total number of words, number of different words and the type-token ratio for the whole sample, the first 50 utterances or the first 100 words; the count for every utterance and the reason any was left out; the spread of utterance lengths and the five longest; a word list; Brown’s stage for the MLU; and a record of samples by student code with MLU over time. Prints a report and downloads the utterances, the word list and the record as spreadsheets.
Who it is for: Speech-language pathologists, SLP assistants working under their supervision, graduate students in clinical practicum, and early intervention and preschool teams that take language samples. Student codes or initials only; the page refuses a name.
Format: Browser tool. Type or paste a transcript and the results update as you type. Prints a report; downloads spreadsheets (.csv); export and import a file.
Access: $12 one-time, yours on every device you sign in on; the tool opens once you are signed in with it. Included with Caveat Classroom and Whole-school licenses. Also in the Speech & Language toolkit ($79) and the Teaching Suite pass ($199), and 1 more bundle. Everything you type stays in this browser; nothing is sent to Caveat.
Where it lives: The Speech & Language space in Caveat Teaching.
Support: Questions, a correction or a request: team@caveatacademic.com.

How to use it

Transcribe the sample one utterance per line. Start the child’s lines with C: and each other speaker with their own letter, or leave the letters off if every line is the child’s.
Put fillers, repetitions and false starts in parentheses, write X for an unintelligible word, and end an abandoned utterance with >. The page leaves those out as the marks say.
Put a slash before each bound morpheme: duck/s, want/3s, roll/ed, eat/ing, he/’s. Mark contractions does the apostrophe ones for you; the Words tab lists words that may still need a slash.
Read the results beside the transcript, then open Utterances to check any count you doubt against the line it came from.
Save the sample under the student code and print the report. Next time, save again and compare the two.

Open the calculator

How the counts are made

The page counts what the transcript marks. It does not guess at morphemes.

One line of the worked example, then the whole sample: 189 morphemes and 161 words in 52 counted utterances, and 82 different words among 161.

What is counted

An utterance is counted when it has at least one word, no X, and does not end in > or ^. Words inside parentheses, braces or brackets are skipped, and so is a word that starts with *. Each word left is one morpheme, plus one for every slash in it.

Following Brown, give a slash to plural, possessive, third person singular, regular past and progressive endings, and to the second part of a contraction. Leave whole: irregular past forms (went, fell), irregular plurals, diminutives (doggie), compound words and names, reduplications (night-night), and gonna, wanna and hafta. An over-regularized past such as eat/ed gets the slash, because the child applied the ending. Guides differ on don’t, won’t and let’s; the helper leaves them whole.

MLU, words and the ratio

MLU in morphemes is the morphemes in the counted utterances divided by the number of those utterances; MLU in words divides the words. In children aged 3;0 to 3;10, Parker and Brorson found the two correlated at .998, so MLU in words is a fair check when marking is in doubt.

Total words counts every word in the counted utterances. Different words counts each root once, so spell a root the same way each time (cry/ed, not cri/ed). The type-token ratio is different words divided by total words. It falls as a sample grows, so compare only samples cut to the same size. Watkins and colleagues found that different words in a fixed-size sample separated children with language impairment from their peers when the ratio did not.

Brown counted 100 utterances. Many clinical protocols accept 50, and the page says when a sample is smaller.

What the stage says

Brown’s stages are bands of MLU: Stage I from 1.0 to 2.0, II to 2.5, III to 3.0, IV to 3.75 and V to 4.5. The ages printed beside them (about 12 to 26, 27 to 30, 31 to 34, 35 to 40 and 41 to 46 months) are approximate. The page names the band and stops there: no percentile, no standard score, no diagnosis. That judgment is the clinician’s, across the whole assessment.

Sources

Brown, R. (1973). A First Language: The Early Stages. Harvard University Press. The rules for counting morphemes (p. 54) and the five stages defined by MLU.
Miller, J. F., & Chapman, R. S. (1981). The relation between age and mean length of utterance in morphemes. Journal of Speech and Hearing Research, 24(2), 154–161. The basis for the approximate ages usually printed beside the stages.
Parker, M. D., & Brorson, K. (2005). A comparative study between mean length of utterance in morphemes (MLUm) and mean length of utterance in words (MLUw). First Language, 25(3), 365–376.
Watkins, R. V., Kelly, D. J., Harbers, H. M., & Hollis, W. (1995). Measuring children’s lexical diversity: Differentiating typical and impaired language learners. Journal of Speech and Hearing Research, 38(6), 1349–1355.
SALT Software. Why do we mark some bound morphemes and not others (saltsoftware.com), on the slash convention, root spelling, and leaving irregular forms, comparatives and gonna or wanna unmarked. The parentheses, X and slash marks here follow SALT’s widely used conventions; this page is not SALT and is not affiliated with it.

The worked example is made up, including the child’s code and age. Counts depend on transcription and marking decisions, which stay with the clinician. A language sample is one part of an assessment; this page reports counts and is not a diagnosis. Transcripts stay in this browser. Support: team@caveatacademic.com.

Mark the morphemes.The page counts.