Grid size

Also called Cell count, Number of cells, Button size, Grid layout

How many cells fit on a page, and what fewer or more actually costs: bigger targets and fewer words, or more words and a harder reach.

What it is

Grid size is the number of cells on a page of an AAC system: a 4 by 3 grid has 12, a 6 by 5 has 30, a 10 by 8 has 80. On a fixed-size screen, more cells means smaller cells. The number is the single setting that most shapes what a person can say and how easily they can say it, and it is chosen at assessment and revisited as the person changes.

Page sets typically ship in several sizes, from a handful of cells to over a hundred, using the same organisation so a person can move up without everything moving.

Who it can help

The decision affects everyone with a grid. Smaller grids suit people whose touch is imprecise, whose vision needs large symbols, who are at the beginning of symbol use, or who are overwhelmed by a busy screen. Larger grids suit people with accurate access and a lot to say, because every word on the home page is a word that needs no navigation.

The mistake in both directions is common. A grid kept small "until they're ready" for years starves a person of language; every word that doesn't fit is a folder away or absent. A grid sized for an adult's fingers on a child with athetoid cerebral palsy produces mis-hits and, in time, a person who stops trying.

How it works

Cell size is set by access, not by language. The question is: what is the smallest target the person can hit reliably, on a bad day, with their chosen access method? A keyguard or adjusted touch settings can make a smaller cell hittable. For eye gaze, the tracker's accuracy sets the floor.

Then vocabulary is set by cell count. A rough guide: 12 to 20 cells hold a beginner core; 30 to 60 hold a working core and a fringe strip; 80 and above hold a large core with most fringe one tap away. Bigger grids reduce navigation, which is often the trade that helps most.

Growing a grid should not move words. Good page sets hide cells and reveal them in place, so that the 20-cell layout is the 60-cell layout with 40 cells masked. See motor planning.

Getting started

Test the touch, not the language. On a tablet, open a page with cells of various sizes and see what the person hits accurately when relaxed and when tired. That is the floor.

Then go bigger than feels comfortable. If the person can hit a 40-cell grid, a 40-cell grid with cells hidden and revealed over time serves them better than a 12-cell grid they will outgrow.

Ask what the page set's growth path is before committing: does the 20 become the 60 without moving anything? If nobody can answer, that is a warning.

Where to get help

A speech and language therapist, often working with an occupational therapist on access, chooses grid size at AAC assessment. ACE Centre publishes guidance on cell size and growth paths for the main page sets. CALL Scotland has printable boards in several sizes to try on paper first.