Notices changes in number of objects/images or sounds in group of up to 3.
Observe whether the child: notices changes in number of objects/images or sounds in group of up to 3.
What it looks like
Three ways this behaviour shows up as a child grows. Each level includes everyday moments to watch for.
Emerging
Just starting
Sometimes pauses, looks longer, or re-orients when a 1–3 set changes by one, especially with adult cueing, but often misses the change.
What you might see
Adult shows two toys, then removes one; child continues looking at the remaining toy without checking the removed location or adult's hand.
Adult makes three taps, then repeats with two; child shows no pause, facial change, or re-orientation toward the sound source.
When one of two toys is covered, child briefly stares at the covered spot only after the adult points or says ‘where?’.
Looks longer when a picture changes from one item to two, but does not reliably reach, search, or vocalise about the change.
Expected
On track
Regularly notices a +1/‑1 change in a 1–3 set, shifting gaze or reaching to check the missing/added item in familiar play.
What you might see
With three blocks on the tray, when one is slid behind a book, child immediately reaches behind the book to retrieve it.
When adult switches from two drum beats to three beats, child pauses and turns toward the drum, then looks to the adult for more.
Exceeding
Going further
Shows clear expectancy in small-set games and searches immediately for a missing item or shows surprise when the ‘wrong’ number appears.
What you might see
During a ‘three kisses’ routine, child leans in and waits for the third kiss; if the adult stops at two, child vocalises/leans in again.
Given three identical cups, child watches as one is removed; then reaches toward the removed cup or crawls to where it was placed.
Child intentionally drops one of two toys off the tray, then looks up at the adult and back to the tray as if checking the change.
Starts banging a spoon twice, pauses, then bangs a third time and looks at the adult, repeating the pattern.
Try this at home
Small everyday moments where you can notice this behaviour without setting up anything special.
During play, place 2 toys on the mat and say ‘look—two!’ Then hide one under a cloth; notice whether your child searches for the missing toy or looks surprised.
At snack, put 1, then 2, then 3 pieces of food on the tray; watch whether your baby notices when you add one more or take one away.
In a sound game, make 2 claps then 3 claps; see if your child pauses, looks at you, or vocalises more after the change.
While reading a picture book, point to a page with 1–3 repeated items; turn to a page with a different number and notice whether your child stares longer or points/reaches.
Connected behaviours
Behaviours that scaffold, follow, or co-emerge with this one.
