At that age, he was right in the kitchen with me doing work!
Chair up a the sink, run the water on low, give him colander, measuring cups, spatulas, whatever and wash them up. Put a towel under chair and take their shirt off.
Sit on floor and organise pots and storage containers
Wash lettuce, break beans in half, wash potatoes
Assist me in stirring, getting things out of fridge or cupboard.
Etc....
HTH,
A x