“If you drop a little toy, like a pom-pom, into a bottle with a narrow neck and hand it to {child_name}, will {he_she} tip the bottle up to get the toy out?”
Follow-up: “Does {he_she} figure it out without you showing, or do you usually need to demonstrate first?”
Not yet
Holds the bottle but doesn't try to get the toy out
Emerging
Gets the toy out only after you show how
Developing
Works it out {him_her}self after a bit of trying
Secure
Tips the bottle straight away to get the toy out, no demonstration needed
This little puzzle is a classic means-end problem — you can absolutely keep it as a play activity.