This is a great activity for when parents will be traveling away from their children on a trip.
Write a special note for each day you will be away. This could be set up like an advent calendar where they see one for each day and can help count down the day until your return. Or, you could have your caregiver hide the note for the next day somewhere in the house and the child can look for their note each morning.
To expand on this, have the child leave a note, or make like a diary entry back to the parents each day saying what they did that day, or expressing that they miss them and love them. The parents will love to read these when they return!
This could also be modified for childcare/preschool settings, especially for preschoolers experiencing separation anxiety.