From Summer Activities for Children, Part 1:

Make a calendar with the birthdays of relatives and friends that are important to your child.

Use the calendar to send cards. You can have your child make a card on the birthdays as they come up.

Or, if the child is old enough, you could teach him how to send e-cards or notes.

Come back to Daily Parenting Tips each day for another fun activity.

See more activities at Summer Activities for Children (2015), Part 1.