Hi, your children's parents will be a great source of information for this. Find out what activities everyone enjoys at home and importantly what sensory concerns and recommendations exist eg. audio/noise, textures, tastes, smells, light/dark and sight ie if particular objects or animals are liked/disliked.
Concentration and focus depends on a child's level of interest and the motivation to engage.
Can you use the children's interests to encourage them to practice fine motor skills such as using scissors, pencils and paintbrushes, wind-up toys, blowing bubbles through handheld wands, using a keyboard/button pressing, interlocking bricks, jigsaw puzzles,
opening eggs to hide items inside. Finger gym,
frog tiddly winks, threading?
Best wishes xx