Recently I watched a boy, a very active boy, become completely focused. He stayed at a table, working, for longer than I've ever seen him work at one time. What was he doing? He was scooping and pouring and touching barley.
I purchased the barley at the grocery store. We poured the barley in a plastic container and added a few repurposed scoops and small bowls.
He poured and measured. He slid his hands down into the barley, completely covering them. I think the texture and the way the barley poured was the attraction.
I've watched different kids enjoy the scooping and pouring, the measuring and experimenting. You can use a variety of materials, all with slightly different properties, for kids to explore--beans, dried pastas, rice. Add measuring spoons and cups. Or plastic cups. Or empty food containers.
My friend became completely absorbed in the activity. Usually he is bouncing from one thing to another. (And that's okay.) But something so simple became so engaging.