SCS Conversation Engine
Most AAC apps stop at “tap a word, hear it spoken.” Meadow keeps the conversation going.
When a child taps “banana” in most AAC apps, the iPad says “banana” and that’s it. The child has to start over for every new thought. That’s a soundboard, not a conversation tool.
Meadow does something different. After the child taps “banana” and hears it spoken, three follow-up options appear instantly — like “I want banana,” “yummy banana!” and “more banana.” The child taps one, it speaks, and new follow-ups appear. We call this the Speak → Choose → Speak loop, or SCS.
The child isn’t just pressing buttons. They’re having a real back-and-forth exchange — the same way language naturally develops through conversational turns.
Three developmental tiers, one system
Every child develops at their own pace. The SCS engine adjusts its behavior based on the child’s developmental tier — set by the parent or speech therapist in the settings. A younger child who is just learning cause-and-effect gets a simpler experience. An older child who is starting to build sentences gets the full conversation loop.
~12–18 months
- ✓ Tap a word, hear it spoken. That’s it.
- ✓ No follow-ups, no conversation loop
- ✓ Single words only — “banana,” “milk,” “more”
- ✓ Focus: learning that tapping makes something happen
~18–30 months
- ✓ SCS loop is active with 2-word follow-ups
- ✓ “want banana,” “more milk,” “no juice”
- ✓ Three suggestions appear after each tap
- ✓ Focus: combining words to express more
~30–48 months
- ✓ SCS loop with 2–3 word follow-ups
- ✓ “I want banana,” “give me milk”
- ✓ Richer variety of follow-up types
- ✓ Focus: expressing complete thoughts
These tier behaviors come directly from M1-003 (Interaction Design). Tier 1 children experience the companion’s guided engagement cycle — Spotlight → Present → Wait → Celebrate → Advance — with expectant pauses of 30–45 seconds at Tier 1, 10–15 seconds at Tier 2, and 5–10 seconds at Tier 3. The SCS conversation loop activates only at Tier 2+, where the child has moved beyond cause-and-effect learning into intentional word combination. See Interaction Design for the full pathway specifications.
Scaffolding levels — parent-controlled
Parents or therapists can also adjust how much help the app provides, independent of the developmental tier. This is set in Settings behind the parent gate.
3 Suggestions
The default. Three follow-up options appear after every word. Best for children who are still learning to use follow-ups.
1–2 Suggestions
Fewer choices for children who are gaining confidence. Reduces visual clutter while still offering help.
Words Only
No follow-ups at all. The child taps words directly, like Tier 1. For children who have outgrown scaffolding.
How Meadow picks the right follow-ups
When a child taps a word, the app doesn’t just show random phrases. It runs through a careful selection process to show the most useful, varied, and contextually appropriate follow-ups. Here’s how it works, step by step.
Find matching follow-ups
Look up all the follow-up phrases that connect to the word the child just said, filtered by the child’s developmental tier. A Tier 2 child only sees 2-word combos; a Tier 3 child sees longer phrases too.
Prefer the current scene
If the child is in the Kitchen scene and taps “want,” kitchen-specific follow-ups like “want banana” and “want milk” appear first. Scene context makes suggestions feel natural and relevant.
Mix different types of communication
The app ensures variety. Instead of three requests (“want banana,” “want milk,” “want juice”), it mixes in a comment (“yummy banana!”) and a feeling (“banana yay!”). This exposes the child to different ways of using language.
Avoid repetition
If the child has tapped “banana” three times in a row, the app shows different follow-ups each time. Previously shown suggestions get shuffled to the back of the line.
Fill in the gaps
If there aren’t enough authored follow-ups for a word, the app automatically generates simple ones like “more banana,” “no banana,” or “banana please.” The child always gets three choices.
Communication types
Speech therapists call these “pragmatic functions” — the different purposes a sentence can serve. Meadow ensures follow-ups span multiple types so children experience the full range of communication, not just requesting.
Requesting
Asking for something. “want banana,” “more milk”
Protesting
Saying no. “no bath,” “don’t want”
Greeting
Social hellos. “hi mommy,” “bye bye”
Asking
Seeking information. “where mommy?” “what that?”
Feeling
Expressing emotions. “happy!” “sad” “I love you”
Directing
Telling someone to act. “come here,” “look!” “help me”
These eight communication functions trace to Beukelman & Light’s Participation Model, documented in M1-006 Clinical Traceability. The M1 framework identifies seven core functions: Requesting, Refusing, Expressing Feelings, Commenting, Social Routines, Directing, and Answering. The SCS engine’s pragmatic function tags ensure every follow-up suggestion maps to one of these clinically validated communication purposes.
Why variety matters
Research on early language development shows that children who are exposed to diverse communication functions — not just requesting — develop broader conversational skills. Many AAC apps inadvertently train children to only make requests because that’s the easiest interaction to model. By mixing follow-up types, Meadow ensures the child practices commenting, protesting, greeting, and feeling — the full toolkit of human communication.
See it in action
Three real examples showing the SCS loop at work across different scenes and tiers. Notice how each turn produces new, contextually relevant follow-ups.
Snack time conversation
Turn 1: Child taps “banana” → iPad speaks “banana!” → three follow-ups appear.
Turn 2: Child taps “want banana” → iPad speaks “want banana!” → new follow-ups appear for the next thought.
Bedtime routine
Turn 1: Child taps “sleep” → iPad speaks “sleep!” → longer, richer follow-ups appear for Tier 3.
Turn 2: Child taps “I want sleep” → iPad speaks the full phrase → follow-ups continue the thought.
A full conversation at the playground
This shows the loop running through three consecutive turns — the child driving a real conversation about what they want to do at the park.
Three turns, zero navigation. The child drove the entire conversation from a single starting word.
Communication comes first. Always.
The SCS engine is designed with several non-negotiable safety rules that protect the child’s communication experience.
Communication is never interrupted
Celebrations, animations, and companion reactions always queue up and wait. If the child is mid-conversation — follow-ups visible, words being spoken — nothing cuts in. The child’s voice always takes priority.
Feelings are immediate
When a child taps “sad” or “angry,” the word speaks instantly. It does not trigger a conversation loop or force follow-ups. Expressing a feeling should never be complicated. One tap, one word, heard.
12-second timeout
If the child stops interacting, the speech bubble and follow-ups clear after 12 seconds. This prevents a stale conversation from confusing the child. The timeout is configurable by the parent in Settings.
Tier 1 is protected
Children at the earliest developmental stage (Tier 1) never see the SCS loop. Their experience is simple cause-and-effect: tap a picture, hear the word. No follow-ups, no choices, no cognitive overload.
Research foundation
The SCS loop is grounded in how children naturally acquire language. Decades of research in speech-language pathology show that children learn to communicate through conversational turns — back-and-forth exchanges where each person responds to the other. Single-word drills teach vocabulary, but conversational turns teach communication. The SCS loop brings this principle into the AAC app experience, giving every child the opportunity to practice real conversational interaction.
The engine is built and tested
The SCS Conversation Engine was assembled from five components, each depending on the one before it. All five are complete, integrated, and passing tests on the simulator. iPad 9 hardware validation happens at milestone review.
Follow-Up Data
Phrases tagged by trigger word, scene, tier, and communication type
Selection Algorithm
5-step process: match, rank, diversify, avoid repeats, fill gaps
SCS Loop
The state machine — speak, choose, speak again
Follow-Up Pills
Tappable buttons with Fitzgerald Key color coding
TTS Integration
Every follow-up speaks aloud on tap
Content vs. engine
The engine is complete — it can accept any number of follow-up phrases and run the full SCS loop. Right now it has ~20 test entries to validate the algorithm. In M3 (Kitchen Scene), this engine gets loaded with 200+ scene-specific follow-ups covering every Kitchen vocabulary item. The engine scales to that volume without changes.
How we know it works
Each criterion is a testable checkpoint. Green items pass in automated tests today. The remaining item needs M3 Kitchen content to validate fully.
| ID | What We Test | Must Pass | Status |
|---|---|---|---|
| M2-003 | Tier-appropriate combinations | The engine produces follow-ups matching the child’s tier. Tier 1: no follow-ups. Tier 2: 2-word combos. Tier 3: 2–3 word combos. Full coverage of every Kitchen item comes in M3. | 🟡 |
| M2-004 | Follow-ups appear instantly | After tapping a Tier 2 or Tier 3 word, speech fires and 3 follow-up suggestions appear within the 400ms word-to-speech budget — fast enough that the child perceives them as instant. | 🟢 |
| M2-004 | Communication type diversity | The 3 follow-up suggestions span at least 2 different communication types (for example, one request and one comment — not three requests). | 🟢 |
| M2-004 | Loop runs without errors | The SCS loop runs for at least 5 consecutive exchanges without errors, freezes, or crashes. | 🟢 |
| M2-004 | Timeout clears the bubble | If the child stops interacting, the speech bubble and follow-ups clear after 12 seconds. No stale conversations remain on screen. Timeout is configurable by the parent. | 🟢 |
Testing approach
19 automated tests verify the engine on every build. Performance will be validated on a real iPad 9 (not just the simulator) at milestone review to confirm the experience matches what an actual child would feel.
The engine is ready — now it needs a world to live in
The SCS conversation engine is complete and tested. The next milestones fill it with content and connect it to the rest of Meadow.
M3: Kitchen scene follow-ups
200+ authored follow-ups for every Kitchen vocabulary item — fridge, stove, table, snacks, drinks, utensils. This is where the engine goes from test data to a real conversation experience.
Companion integration
The companion character will react to SCS conversations — signing along, celebrating milestones, and modeling language. The engine already fires events the companion can listen to.
Celebration triggers
The celebration system will watch for conversation milestones — first 3-turn conversation, new word combinations, returning to a word after time away — and respond with contextual celebrations.
All scenes
In M4, every routine scene (Bath, Bedtime, Getting Dressed, Playtime) gets the same follow-up depth as Kitchen. The engine scales without changes — only the content library grows.
Commenting
Describing or observing. “big dog!” “yummy banana”