Baseball is like 80% mental. There’s a reason they call it a thinking game.
I won’t supply 1000’s of scenarios, but your kids have an idea of where they tend to play, and where they want to play for that matter. Pick some specific situations, have them close their eyes, and walk them through the situation in detail. Have them picture exactly what is happening, and what they do.
Here is an example:
You are playing shortstop. There are no runners on and no outs. Pitch #1 is a ball. Next pitch is a strike. Pitch #3 is hit on the ground to you. What are you doing with it?
They should be visualizing themselves prep stepping each pitch, and then charging and fielding the ball, setting themselves, and throwing to first.
Obviously, you can’t see what they’re seeing, but talking them explicitly through the first one will get their imagination flowing.