"How many words should be on the device?"
It's one of the first questions parents ask when they start using AAC. It comes up in evaluations, therapy sessions, and every online parent group. And the honest answer is: it depends. But "it depends" isn't helpful on its own, so let's break down what it actually depends on and how to make good decisions for your child.
Why This Question Is So Common
The question makes perfect sense. You're staring at a blank AAC app or a brand new device, and you need to decide: should you start with 4 big buttons? 20? 60? More? It feels like a make-or-break decision. Pick too few words and your child won't have enough to say. Pick too many and they might get overwhelmed.
The good news is that this decision is less fragile than it feels. There's no single correct number. But there are principles that will guide you toward a setup that grows with your child instead of holding them back.
Grid Sizes and What They Mean
AAC apps typically organize vocabulary into grids. The grid size determines how many words appear on a single screen. Here are the most common options:
4-cell grid (2×2): Four large buttons. Often used as a starting point for very young children or individuals with significant motor challenges. Provides limited vocabulary per screen but maximum target size for easy selection.
9-cell grid (3×3): Nine buttons. Still fairly large targets, with room for a small but functional vocabulary set on one page.
20-cell grid (4×5): A popular starting point for many AAC users. Enough room for a solid core vocabulary while keeping button sizes manageable.
36-cell grid (6×6): Common for users who can handle smaller targets. Allows a much larger vocabulary to be visible at once.
48-cell grid (6×8 or 8×6): A step up that provides even more words per screen. Often used with older children and adults.
60+ cell grid (various configurations): High-density layouts used by experienced AAC users and adults. These pack a large vocabulary into a single view with smaller targets.
The grid size affects two things: how many words your child can see at once, and how large each button is. Larger grids mean more vocabulary visible per screen but smaller buttons. Smaller grids mean fewer visible words but larger, easier-to-hit targets.
The Difference Between Visible Words and Available Words
Here's something important that many parents miss. The number of words visible on one screen is not the same as the total number of words available on the device.
Most AAC apps use pages, folders, or categories to organize vocabulary. A device with a 20-cell grid might have hundreds of words organized across multiple pages. The child navigates between pages to find what they need.
So when someone says "start with fewer words," they might mean:
- Start with a smaller grid size (fewer words visible at once)
- Start with fewer total words available (removing pages or hiding vocabulary)
- Both
These are very different decisions, and the second one deserves careful thought. Reducing the grid size to match motor abilities is smart. Removing vocabulary that the child "doesn't use yet" is often counterproductive.
Motor Planning: Why Consistent Locations Matter
One of the most important concepts in AAC is motor planning, sometimes called motor automaticity. This is the idea that with enough practice, finding and pressing a word on an AAC device becomes automatic, like typing on a keyboard without looking at your fingers.
Baker, Hill, and Devylder (2000) emphasized the importance of consistent motor patterns in AAC access. When a word always lives in the same location, the user develops a motor pathway to that word. Over time, they don't need to visually search for it. Their hand or finger just goes there.
This is why word location should stay consistent as vocabulary grows. If "want" is in the top-left corner on a 20-cell grid, it should still be in the top-left corner when you move to a 36-cell grid. Good AAC apps are designed with this in mind. They expand the grid without rearranging existing words.
When evaluating AAC apps, check whether the app supports grid growth without relocation. This is a critical feature that separates well-designed systems from ones that will cause frustration down the road.
The Danger of Restricting Vocabulary
This brings us to one of the most common mistakes in AAC: removing words because the child isn't using them yet.
It happens all the time. A parent or therapist looks at a device with 200 words, sees the child using 10 of them, and thinks "this is too much. Let me simplify." They strip the device down to just those 10 words, or maybe 15 to 20.
The intention is good. The result is often harmful.
Beukelman and Mirenda, in their foundational textbook on AAC, make the case that restricting vocabulary limits language development. A child can't learn to use a word if the word isn't available. Exposure precedes use. This is true for speaking children and AAC users alike. A typical 2-year-old hears thousands of words they don't use yet, and nobody removes those words from their environment.
Light and McNaughton, in their extensive research on communicative competence, argue that AAC users need access to a robust vocabulary to develop genuine linguistic competence. This includes words they aren't using today but will need tomorrow.
The analogy that helps most parents is a bookshelf. You don't remove books from your child's bookshelf because they haven't read them yet. The books are there for when they're ready. Words on an AAC device work the same way.
So How Many Words Should You Actually Start With?
Here's the practical guidance, broken into steps.
Step 1: Match the grid size to motor abilities
Start with a grid size your child can reliably access. If they have strong fine motor skills, a 20-cell or 36-cell grid might work from the beginning. If they struggle with smaller targets, start with a 9-cell or even a 4-cell grid.
The key word here is "reliably." If your child can hit the right button about 80% of the time, the grid size is probably appropriate. If they're hitting the wrong button half the time, the targets are too small.
Step 2: Keep all vocabulary available
Even if you start with a smaller grid, don't strip out pages or folders. Let the full vocabulary exist in the system. Your child may surprise you by navigating to words you didn't expect them to use.
Step 3: Focus on core vocabulary first
A few hundred core words cover the vast majority of daily communication. These high-frequency, flexible words like "want," "go," "more," "not," "help," and "that" are the ones your child will use across every setting and every activity.
For a detailed list, see our core words list for AAC. And if you're wondering why core words outperform nouns, this comparison explains it.
Step 4: Add fringe vocabulary as needed
Once core words are in place, add context-specific nouns and other fringe vocabulary. Favorite foods, family names, pets, beloved characters. These words give conversations flavor and specificity, but core vocabulary gives them structure.
The difference between core and fringe matters a lot when you're deciding where to focus limited teaching time. Read more about this in core vocabulary vs. nouns-only approaches.
Step 5: Grow the grid over time
As your child's motor skills and vocabulary grow, increase the grid size. This gives them more words visible at once without navigating to different pages. A child who starts on a 9-cell grid might move to 20, then 36, then 48 over months or years.
The pace depends entirely on the individual. There's no timeline that applies to everyone.
What About Presume Competence?
The principle of presuming competence is central here. It means assuming your child is capable of more than they're currently showing. In vocabulary decisions, it means:
- Offering more words than your child currently uses
- Not gatekeeping vocabulary behind "readiness" criteria
- Letting your child explore the device freely, even if it seems random at first
- Trusting that exposure and modeling will lead to growth over time
Presuming competence doesn't mean throwing a 60-cell grid at a toddler with no support. It means not artificially limiting what's possible based on what you've seen so far.
Common Questions
"My child just presses random buttons. Should I remove words?"
No. Pressing random buttons is exploration, and it's a normal stage. Every child who learns to use an AAC device goes through it. They're learning how the system works, what happens when they press different things, and where words live. This builds the foundation for intentional use later.
Instead of removing words, model meaningful use alongside their exploration. When they accidentally hit "go," say "go! Let's go!" and go somewhere. Turn their random presses into communication.
"The therapist said to start with only 4 words."
Some therapists recommend starting with a small focused set. This can make sense for initial teaching, but it should be about what you're actively teaching, not what's available on the device. You can focus your modeling on 4 to 6 words while keeping hundreds of others accessible.
Think of it like this: a first-grade teacher focuses on specific reading skills each week, but they don't lock up the library.
"My child uses a high-tech device but still only says a few words."
The number of words on the device is not the same as the number of words the child uses. That gap is normal and expected. A speaking 18-month-old understands hundreds of words but only says 10 to 50. AAC users follow the same pattern. Receptive vocabulary (what they understand) always outpaces expressive vocabulary (what they produce).
The solution is consistent modeling, patience, and time.
The Bottom Line
There is no magic number of words that belongs on an AAC device. The right amount depends on your child's motor abilities, communication needs, and developmental stage. But here's what the research consistently supports:
- Match grid size to motor access. Bigger buttons for less precise movements, smaller buttons as accuracy improves.
- Don't restrict vocabulary. More available words is almost always better than fewer.
- Prioritize core vocabulary. 200 to 400 words cover most of what we say.
- Keep word locations consistent. Motor planning depends on predictability.
- Presume competence. Your child can handle more than you think.
The goal isn't to find the perfect number. It's to create a system that has enough language for today and room to grow for tomorrow.