MV T3.01Object Permanence Box
The infant drops a ball through a hole in the top of a wooden box and watches it roll out onto the attached tray.
Safety
- The ball must be larger than 1.75 in. (44.4 mm) across; federal rules ban balls for children under 3 that pass through a hole that size (16 C.F.R. 1500.18(a)(17)), and a 5 cm (2 in.) ball is larger with a margin.
- Check knitted balls weekly for loose yarn and wooden balls for cracks, and remove any that are damaged.
- Wash the ball and tray daily, because infants mouth them.
Presentation
- 1
Carry the box to the mat or low table where the infant is sitting. Sit beside them.
- 2
Place the box in front of the infant with the tray toward them. Put the ball on the tray.
- 3
Pick up the ball slowly with your whole hand and hold it above the hole so the infant can see it.
- 4
Open your hand and let the ball drop through the hole. Say nothing.
- 5
Wait with your eyes on the tray. The ball rolling out onto the tray is the point of interest.
- 6
Drop the ball once or twice more at the same slow speed.
- 7
Take your hands away and let the infant take the ball. If they bang or mouth it first, wait; do not guide their hand.
- 8
When the infant turns away or stops, place the ball on the tray and return the box to the shelf.
Extensions, easiest to hardest
- Box in which the ball rolls down an inside ramp before it appears, so it is out of sight longer
- Box with a sliding lid over a compartment: the infant hides an object and slides the lid to find it
- Ball tracker: a wooden frame with three sloped tracks, down which a ball at least 5 cm (2 in.) across rolls from one track to the next
Control of error
The ball returns to the tray only when it is let go over the hole; its return confirms each drop.
Ready to move on when the child…
- Lets go of the ball over the hole on the first try most times
- Looks at the tray before the ball rolls out
- Repeats the cycle several times in a row without adult help
Guide note
Sources give first-offer ages from 6 to 12 months, and some sellers list up to 18 months; most Montessori infant sources place it at about 8–10 months, once the infant sits steadily without support and can let go of an object on purpose. Some sold boxes include 4.5 cm balls, which are larger than the federal small-ball limit by less than 1 mm; a 5 cm ball is the safer choice.