One of them is ready. Standing there, holding the thing, asking when.
The other one is halfway through something else and has not looked up. Or they are both ready and want different versions of it, which is the same afternoon with an extra negotiation attached.
You do not have to get them to agree, and you do not have to get them moving at the same speed. You can set the thing up so that neither of those is required. Here are three ways to do that. Take whichever one suits the afternoon in front of you.
Two jobs instead of one
Hide the Object splits the afternoon into two roles. One child hides it, the other one looks for it. The seeker waits while the object is placed, then looks, and the hider can guide from where they are.
Pick an object that is safe-sized for the youngest child in the room. It stays in view rather than inside anything, but not somewhere obvious. Behind a chair leg. On a shelf at their own height. Half behind the fruit bowl with a bit of it still showing.
Swap the roles only if both of them want to. There is no rule saying they have to alternate. If one of them hides it every single time, that is still the activity.
Hide the Object
One player hides a small object in the room and everyone hunts for it in turns.
Shaped to your child and the moment you are both in.
Two lanes, or one roller and one resetter
Sock Ball Bowling can be arranged either way. One child rolls and the other resets the targets, which is two jobs again. Or set up a separate lane each, so nobody is queuing behind anyone.
You need lightweight plastic containers as targets, a soft sock ball, and clear floor space. Tape on the floor gives you a line to roll from, though it is optional.
Nothing here needs a score. There is no winner built into it unless somebody decides there is.
The safety part, plainly. An adult stays in the room. Clear trip hazards and knocked-down items as you go. The rolling line stays where it is rather than creeping forward. Lightweight plastic targets only, so no glass and no heavy ceramic. If a bottle is weighted with water or sand, check that it is fully sealed before every round.
Sock Ball Bowling
Stack empty containers - cups, bottles, or small boxes - at one end of a hallway or room. Roll a ball or bundled socks to knock them down. Reset and repeat.
Shaped to your child and the moment you are both in.
Same table, separate paper
Sticker Story Scenes gives everybody a sheet of their own. One sheet each, or one patch of the table each, however you want to divide it up. The scenes can connect if that is what they want, and they can stay entirely unrelated if it is not. Neither child has to wait for the other to finish anything.
One thing to check first. Small stickers are a choking and ingestion risk. For a child aged 2 to 3, an adult stays within arm’s reach throughout. For every child under 3, an adult also keeps them in direct line of sight throughout. Check that every sticker piece is at least 3 cm before the child handles it.
Sticker Story Scenes
Child creates a story or scene by placing stickers in a sequence on paper, then describes what's happening.
Shaped to your child and the moment you are both in.
Watching, leaving, coming back
Whichever of the three you set up, treat joining as optional.
Standing and watching for a while before picking anything up counts. So does leaving halfway through, and so does turning up again later and joining the middle of it without asking.
None of that needs pointing out or commenting on. And laying out two sets of materials rather than one means there is still something to come back to.
Start with the setup
Two jobs rather than one. Two lanes rather than one. Two sheets of paper rather than one shared sheet.
You can set any of them up before anybody starts. And if the first one does not suit the afternoon you are in, there are two others here to try.
The setup is the part you get to choose.