40 quick and easy brain-building activity ideas for four-year-olds. The brain of a four-year-old child is continuing to learn and organize through experiences in life. These activity ideas provide hands-on learning throughout the day and support development of all skill areas. Information on how these attentive and fun interactions help a child's brain develop is also included. Brain Insights activity cards are compact and portable, making it easy to jumpstart interactive play anywhere throughout the day.