Builds: Expansion, or Your Sentence Plus One Piece
An expansion is when a coach repeats your sentence and adds one missing piece: a word, a phrase or a linking clause. You say El lobo sopla (The wolf blows). The coach says Sí, el lobo sopla muy fuerte (Yes, the wolf blows very hard). Your idea stays yours. It just comes back one step longer.
Speech-language pathologists (SLPs) use expansion to grow children's sentences. Adults can borrow it as a learning strategy. Learning a language is not a disorder, and neither is an accent.
What is expansion in language learning?
In SLP research, expansion means the adult repeats the speaker's words and adds the missing grammar (Scherer & Olswang, 1984). In adult coaching, the missing piece can be grammar or detail. The rule is the same: keep the learner's meaning and add one thing.
In Edgewise, this move is called Builds. It's one of nine moves a good speaking coach uses.
Expansion vs. recast vs. extension
Three moves sound alike. Each changes something different.
| Move | What it changes | Learner | Coach |
|---|---|---|---|
| Expansion (Builds) | Adds one missing piece | El cerdito hace una casa. (The little pig makes a house.) | Sí, hace una casa de paja. (Yes, he makes a house of straw.) |
| Recast (Fixes) | Fixes one error | El cerdito hace un casa. (The little pig makes a [wrong article] house.) | Sí, hace UNA casa. (Yes, he makes A house.) |
| Extension (Comments) | Adds new meaning | El cerdito hace una casa. | ¡Y el lobo ya está mirando! (And the wolf is already watching!) |
The line can blur. When the missing piece is grammar, such as an article or a verb ending, an expansion also works as a fix. That's why second language research folds expansions into "recasts." For the other two moves, see Fixes and Comments.
What does the research say?
Expansion has a long record in child language research. Here's what the studies show, and what they don't.
Echo first, then own it. Four 2-year-olds were studied as their mothers expanded more. More expansions went with more spontaneous imitation of new two-word combinations. Then the children's own use of those combinations rose and held, while imitation dropped off (Scherer & Olswang, 1984).
A meta-analysis. Recasts, the family expansions belong to, showed average effects of d = .96 on near measures and .76 on broader ones. The review covered 35 studies, 14 of them in the meta-analysis. The authors call the evidence limited and note that study quality varied substantially (Cleave et al., 2015).
Why the contrast helps. In one experiment, 36 children (mean age 5) learned made-up irregular past-tense verbs. They used the correct form more often, with fewer repeated errors, after hearing their error set against the adult form. Plain correct input did less (Saxton, 1997). Saxton calls this Contrast Theory: you learn from the gap between your version and the better one.
Adults, and the silent learner. With adult ESL learners, intensive recasts helped more advanced learners produce higher-level question forms. Learners rarely repeated the recasts. The authors suggest those immediate responses "may be red herrings" (Mackey & Philp, 1998). If you don't repeat the coach's line, it hasn't necessarily failed.
A caveat. Most of this research is with young children. The adult study looked at conversation with ESL learners, not solo practice with an app. Use it as a guide, not a guarantee.
The one-piece rule
Add one piece per turn. One change is easier to notice. In adult classrooms, recasts that made only one change were more likely to be taken up (Loewen & Philp, 2006).
There are three places to add a piece.
| Piece | What it answers | Spanish | Korean |
|---|---|---|---|
| Noun phrase | Which one? What kind? | la casa → la casa de ladrillos (the house → the brick house) | 사자 → 큰 사자 (lion → big lion) |
| Verb phrase | How? Where? When? | sopla → sopla muy fuerte (blows → blows very hard) | 자요 → 나무 밑에서 자요 (sleeps → sleeps under a tree) |
| Linking clause | Why? When? But? | …porque tiene hambre (…because he's hungry) | 사자가 잘 때… (When the lion sleeps…) |
Grammar pieces need a little extra help. Learners tend to notice word feedback more readily than grammar feedback (Mackey, Gass & McDonough, 2000). So when the new piece is an ending or a small word, the coach should stress it.
A four-turn ladder in Spanish
The Tortoise and the Hare. Each coach turn adds one piece. The learner picks it up and adds more.
| Turn | Speaker | Line | Piece added |
|---|---|---|---|
| 1 | Learner | La tortuga camina. (The tortoise walks.) | — |
| 2 | Coach | Sí, la tortuga camina despacio. (Yes, the tortoise walks slowly.) | Verb phrase: how |
| 3 | Learner | La tortuga camina despacio. Y la liebre duerme. (The tortoise walks slowly. And the hare sleeps.) | Learner adds a new idea |
| 4 | Coach | Sí, la tortuga camina despacio mientras la liebre duerme. (Yes, the tortoise walks slowly while the hare sleeps.) | Linking clause: while |
Two short sentences became one linked sentence.
A four-turn ladder in Korean
The Lion and the Mouse.
| Turn | Speaker | Line | Piece added |
|---|---|---|---|
| 1 | Learner | 사자가 자요. (The lion is sleeping.) | — |
| 2 | Coach | 네, 큰 사자가 자요. (Yes, the big lion is sleeping.) | Noun phrase: which one |
| 3 | Learner | 큰 사자가 자요. 생쥐가 와요. (The big lion is sleeping. A mouse comes.) | Learner adds a new idea |
| 4 | Coach | 네, 큰 사자가 잘 때 생쥐가 와요. (Yes, when the big lion is sleeping, a mouse comes.) | Linking clause: when |
Notice what the coach never does. It doesn't add the next plot event. The mouse arrives because the learner said so.
How to get expansions from a tutor
Most tutors either correct everything or nothing. Ask for this instead.
- Ask for it by name. In Spanish: Cuando diga una frase corta, ¿me la repites con un detalle más? (When I say a short sentence, can you say it back with one more detail?) In French: Quand je dis une phrase courte, tu peux la répéter avec un détail en plus ?
- Set the limit. One piece per turn, not five.
- Keep your words. The tutor builds on your sentence, not a new one.
- Don't stop the story. Expansions ride along with the conversation. They aren't a grammar lesson.
How to expand your own sentences
No tutor? Do it to yourself.
- Record a retell. Tell a short picture story aloud.
- Find your three shortest sentences. Write them down.
- Add one piece to each. One to a noun, one to a verb and one linking clause.
- Say each new sentence aloud twice. Echoing is fine. In the toddler study, imitation came before independent use.
- Retell again. Use all three.
For teachers, tutors and SLPs
Expand on the learner's topic, not yours, and add one piece per turn. Stress the new piece when it's grammar. Don't require a repeat. A learner who stays silent may still be taking it in.
FAQ
What is expansion in language learning? Expansion is when a coach repeats your sentence and adds one missing piece: a word, a phrase or a linking clause. Your meaning stays the same, and the sentence gets one step longer.
Is an expansion the same as a recast? Not quite. An expansion adds a piece; a recast fixes an error. Second language research often groups expansions under recasts, because adding missing grammar also corrects the sentence.
Do I have to repeat the expanded sentence? No. In a study with adult ESL learners, recasts helped even though learners rarely repeated them. Repeating is fine if it helps you, but it isn't required.
How much should a tutor add? One piece per turn. One change is easier to notice than several, and a sentence that grows five pieces at once is a new sentence, not yours.
Does expansion work for adults? Most expansion research is with children. Adult studies of recasts, the broader family, show learning benefits, so the logic carries over. Direct tests with adults practicing alone are lacking.
Your next step: Try a story retell in Edgewise. The coach builds on what you say, one piece at a time, and never tells the story for you. Your first retell sets your level. Every round scores story structure and sentence building, then ends with your next piece: one specific thing to add next time.
Join early accessSources
- American Speech-Language-Hearing Association. (n.d.). Accent modification [Practice Portal]. https://www.asha.org/practice-portal/professional-issues/accent-modification/
- Cleave, P. L., Becker, S. D., Curran, M. K., Owen Van Horne, A. J., & Fey, M. E. (2015). The efficacy of recasts in language intervention: A systematic review and meta-analysis. American Journal of Speech-Language Pathology, 24(2), 237–255. https://doi.org/10.1044/2015_AJSLP-14-0105
- Loewen, S., & Philp, J. (2006). Recasts in the adult English L2 classroom: Characteristics, explicitness, and effectiveness. The Modern Language Journal, 90(4), 536–556. https://doi.org/10.1111/j.1540-4781.2006.00465.x
- Mackey, A., Gass, S., & McDonough, K. (2000). How do learners perceive interactional feedback? Studies in Second Language Acquisition, 22(4), 471–497. https://doi.org/10.1017/S0272263100004010
- Mackey, A., & Philp, J. (1998). Conversational interaction and second language development: Recasts, responses, and red herrings? The Modern Language Journal, 82(3), 338–356. https://doi.org/10.1111/j.1540-4781.1998.tb01211.x
- Saxton, M. (1997). The Contrast Theory of negative input. Journal of Child Language, 24(1), 139–161. https://doi.org/10.1017/S030500099600298X
- Scherer, N. J., & Olswang, L. B. (1984). Role of mothers' expansions in stimulating children's language production. Journal of Speech and Hearing Research, 27(3), 387–396. https://doi.org/10.1044/jshr.2703.387