SLP Praxis Child Language and Speech-Sound Practice: Milestones, Cases, and Rationales

Use these six original cases to connect developmental history, language samples, speech patterns and referral decisions. The lesson samples topics in the Praxis assessment and treatment categories; it does not predict item frequency. See the ETS SLP Praxis Study Companion for exam structure and the free sampler for additional questions.

Developmental milestones the Praxis expects

Interpret milestones using the source’s population and the child’s full developmental and language history. ASHA’s milestone resources support monitoring and referral. Learning multiple languages does not cause a speech or language disorder and must not be used to dismiss a concern.

Pre-linguistic communication, babbling, and jargon

• Birth–3 months: Crying and early cooing emerge, with responses to voices and interaction.
• 4–6 months: Vocal play and laughter expand; children respond to voices and take turns making sounds.
• 6–9 months: Canonical babbling begins (reduplicated /bababa/); increased pitch and loudness variation.
• 9–12 months: Variegated babbling (/badagu/); jargon-like intonation patterns; first words may appear around 12 months.

By roughly 10–12 months, many children understand far more than they say and begin using gestures and vocalizations intentionally. A lack of canonical babbling by approximately 10 months is often flagged as a reason to monitor hearing and communication development more closely.

First words and early vocabulary growth

• ~12 months: First words emerge; often names for people, pets, familiar objects, and routines.
• 19–24 months: ASHA’s milestone resource includes using and understanding at least 50 words. This is an age band, not a claim that 50 words is required at 18 months.
• ~18–24 months: Vocabulary growth accelerates; children begin combining words and understanding routine directions.

A vocabulary size below approximately 50 words at 24 months, or no word combinations by 24 months, is widely cited as a reason to consider referral. These cutoffs are not absolute, but they are the thresholds most often used in pediatric screening and early intervention.

Two-word combinations and telegraphic speech

• ~18–24 months: Two-word combinations appear (e.g., "more milk," "daddy go").
• ~24–30 months: Telegraphic speech expands; function words are omitted; early grammatical morphemes begin appearing.
• ~30–36 months: Three- and four-word utterances become common; question forms and negatives emerge.

Calculating and interpreting MLU

MLU in morphemes is total counted morphemes divided by total analyzed utterances. Use a documented sampling and coding method appropriate to the child’s language and dialect. Brown’s stages are a historical descriptive framework, not a diagnostic age conversion. The arithmetic examples below use invented 50-utterance samples; 50 is not a universal minimum for every assessment.

Variation caveat

Assessment should cover the child’s languages and dialects and consider hearing, developmental history and opportunities to use language. Multilingualism itself is not a disorder. Do not interpret an English-only sample as the child’s entire language ability or attribute a delay to bilingual exposure alone.

Speech-sound development and disorders

Speech-sound development moves from early, simple sounds toward later, more complex sounds. Consonants such as /p, b, m, n, h, w/ are acquired earlier; later sounds include /r, s, z, th, l, zh/. Cross-linguistic reviews by McLeod and Crowe (2018) emphasize that acquisition ages vary across languages and studies, so single-age cutoffs are less useful than patterns of error.

Phonological processes and ages of suppression

The table follows ASHA’s Selected Phonological Patterns resource. Its likely elimination ages are guideposts tied to the referenced populations, not universal deadlines. A pattern that belongs to a child’s language or dialect is not an error simply because it differs from mainstream American English.

Articulation disorder vs. phonological disorder

The distinction matters for treatment planning and appears frequently on the Praxis.

• Articulation disorder: A problem with the motor production of individual speech sounds. Errors are often substitutions, distortions, or omissions limited to one or a few sounds. A child who misarticulates /r/ and /s/ but is otherwise intelligible may fit this profile.
• Phonological disorder: A problem with the rule system underlying speech-sound use. Errors form patterns (phonological processes) that affect multiple sounds. A child who fronts velars, stops fricatives, reduces clusters, and glides liquids likely has a phonological disorder rather than isolated articulation errors.

In practice, the line can be fuzzy, and many children show features of both. For exam purposes, look for whether the errors are isolated and motor-based (articulation) or patterned and rule-based (phonological).

Assessment reasoning

When a difference is dialect, not disorder

A dialect is a systematic, rule-governed variety of English shared by a speech community. Dialect features are not errors and do not indicate a disorder. The ASHA Practice Portal on dialects emphasizes that clinicians should assess communication within the child's linguistic community.

Examples of rule-governed dialect features include:

• African American English (AAE): "aks" for "ask," "dese/dem" for "these/them," final consonant deletion in some contexts, copula/auxiliary omission ("he running"), habitual "be," and multiple negation.
• Spanish-influenced English: Final consonant devoicing ("bed" → "bet"), consonant cluster reduction, and /b/ for /v/ substitutions in some contexts.

Assess communication in the child’s language community using appropriate sampling and other measures. If a test’s normative sample or administration is unsuitable, its standard score may not be interpretable. Do not modify scoring and still report a norm-referenced result unless the manual supports that use.

Red flags that justify referral

• No canonical babbling by ~10 months.
• No first words by ~15–18 months.
• Fewer than ~50 words or no two-word combinations by ~24 months.
• Persistent final consonant deletion beyond ~3–3.5 years.
• Persistent fronting beyond ~4 years; persistent gliding beyond the referenced 6–7-year range.
• Poor intelligibility to unfamiliar listeners by age 4.
• Regression of previously acquired speech or language skills.
• Parent or caregiver concern, especially when paired with any of the above.

Gathering the right sample

A good evaluation includes a connected language sample, a hearing screening, parent/caregiver report, and consideration of the child's language(s) and dialect(s). For speech sound assessment, contextual testing, stimulability, and consistency of error patterns help distinguish developmental variation from disorder.

Practice questions

The following cases are original and written for Praxis-style reasoning. Each question has one best answer and full rationales for every option.

Case 1: MLU interpretation

Question: A 3-year-old (36 months) produces a 50-utterance language sample with an MLU of 2.2 morphemes. Sample utterances include "more milk," "daddy go," "big dog," and occasional three-word forms such as "I want cookie." Based on commonly cited norms, which conclusion is most supported?

• A. Interpret MLU with a representative sample and other language measures before drawing a conclusion.
• B. Diagnose a severe language disorder from MLU 2.2 alone.
• C. Discard the sample because utterance lengths vary.
• D. Classify the child as developmentally advanced because a few utterances are longer.

• A. Correct. MLU 2.2 describes this sample. Review its representativeness, coding, the child’s languages and dialects, and other assessment information before interpreting development. This one number cannot diagnose a delay or assign its severity.
• B. MLU alone does not indicate a severe language delay; it is one data point that must be interpreted with age, sample quality, and other measures.
• C. Mixed utterance lengths are normal in a language sample and do not invalidate MLU; the calculation already accounts for variation.
• D. A few longer utterances do not establish advanced development; MLU is an average, and development requires a broader assessment.

Case 2: Phonological process identification

Question: A 4-year-old says "tup" for "cup," "tat" for "cat," and "do" for "go." Which phonological process is primarily demonstrated?

• A. Fronting
• B. Stopping
• C. Cluster reduction
• D. Gliding

• A. Correct. Fronting: the child is substituting alveolar /t/ and /d/ for velar /k/ and /g/. This is a common process but is typically suppressed by approximately 3.5–4 years, so persistence at age 4 warrants monitoring.
• B. Stopping would involve replacing a fricative or affricate with a stop (e.g., "too" for "shoe"), which is not the pattern here.
• C. Cluster reduction would simplify a consonant cluster (e.g., "top" for "stop"), not a single velar sound.
• D. Gliding would replace a liquid /r/ or /l/ with /w/ or /j/ (e.g., "wabbit" for "rabbit"); the errors here involve velars, not liquids.

Case 3: Dialect vs. disorder

Question: A kindergarten SLP evaluates a 5-year-old who speaks African American English at home. The child produces "dese books," "I aks the teacher," and "he running fast." Caregiver report, dialect-appropriate language sampling and dynamic assessment show effective communication consistent with same-dialect peers; no standardized score has been recalculated using altered rules. Which statement is most accurate?

• A. The described productions can be dialect features; the stated assessment does not establish a disorder.
• B. Diagnose a phonological disorder based only on “dese.”
• C. Diagnose a morphology disorder based only on “he running.”
• D. Begin language-disorder treatment solely to eliminate the dialect features.

• A. Correct. These productions are consistent, rule-governed features of AAE (th-stopping, metathesis in "ask," and copula/auxiliary omission). They are dialect features, not evidence of disorder.
• B. Th-stopping is a documented AAE phonological rule; it does not, by itself, indicate a phonological disorder.
• C. Omission of the copula/auxiliary in AAE is a grammatical feature of the dialect, not proof of a morphology deficit.
• D. Dialect features alone do not justify language-disorder treatment. The stated dialect-appropriate assessment supports effective communication; remain attentive to independent evidence of a co-occurring disorder.

Case 4: When to refer

Question: A 4-year-2-month-old consistently deletes final consonants across words in the connected sample ("do" for "dog," "cu" for "cup," "ba" for "bat"). Parents report that unfamiliar listeners understand less than half of what the child says. What is the best next step?

• A. Arrange hearing screening and a comprehensive speech-sound evaluation.
• B. Wait until kindergarten without further assessment.
• C. Begin treatment for /g/ alone without evaluating the pattern.
• D. Diagnose a specific speech disorder from these examples without further assessment.

• A. Correct. Final consonant deletion is typically suppressed by approximately age 3; persistence at 4 years 2 months with reduced intelligibility is a clinical red flag. A hearing screening and comprehensive speech-sound evaluation are indicated.
• B. "Wait until kindergarten" delays evaluation for a child who already has poor intelligibility; the stated concerns already warrant assessment.
• C. Targeting /g/ alone would miss the systematic final-consonant deletion pattern; treatment should address the broader phonological process.
• D. A diagnosis cannot be made from one reported pattern; a full assessment, including hearing and stimulability testing, is required.

Case 5: Articulation vs. phonological disorder

Question: Two 6-year-olds are evaluated. Child A distorts /r/ in all positions but produces all other sounds age-appropriately. Child B fronts velars, stops fricatives, reduces clusters, and glides liquids across many sounds. Which description is most accurate?

• A. A shows an isolated sound-production difficulty; B shows broader patterned speech-sound errors.
• B. Both profiles show only isolated articulation difficulty.
• C. A shows a broad phonological pattern and B only an isolated distortion.
• D. The speech observations prove that neither child has a language disorder.

• A. Correct. Child A has an isolated, motor-based sound production problem consistent with an articulation disorder. Child B shows multiple, rule-based error patterns affecting many sounds, consistent with a phonological disorder.
• B. Child B's patterned errors are not typical of a pure articulation disorder.
• C. Child A does not show the broad phonological rule deficits seen in Child B.
• D. These observations describe speech sounds, not a completed language assessment. They cannot establish that either child has or does not have a co-occurring language disorder.

Case 6: Language sample + milestone integration

Question: During a preschool screening, a 34-month-old produces mostly single words and occasional two-word combinations ("mama shoe"). MLU is 1.4. The parent reports about 75 words used spontaneously. Based on commonly cited norms, which statement is most accurate?

• A. Refer for a comprehensive language evaluation, considering all languages and dialects used.
• B. Diagnose severe language disorder from the screening alone.
• C. Do not calculate MLU because the child uses some single-word utterances.
• D. Treat 75 words at this age as proof of advanced language development.

• A. Correct. At 34 months, most children are producing multi-word utterances regularly and have vocabularies well above 75 words. An MLU of 1.4 and mostly single-word output, even with a 75-word vocabulary, warrants referral for a comprehensive language evaluation.
• B. Severe language delay is too strong a label from screening data alone; referral for evaluation is the appropriate next step, not diagnosis.
• C. Single-word utterances can be included in an MLU calculation; follow the stated sampling and morpheme-coding rules.
• D. A 75-word expressive vocabulary at 34 months is generally considered below the commonly cited average, not above it.

How to use these cases in your study plan

For each case, identify the child’s age and language background, the relevant source population, the sample’s limits and what additional assessment is needed. Explaining those steps is more useful than assigning a diagnosis from one number or a single sound.

For a broader review of the exam structure, read the ETS SLP Praxis Study Companion. For additional practice questions with rationales, visit the free SLP Praxis practice page.