The main must have in my kit is always a small ball. These come in many sizes and varieties, and the only requirement is that they are big enough to kick and for a toddler to grab and hold with both hands with minimal effort.
The simple ball covers so many skills for kids of all ages.
For gross motor, kicking the ball teaches balance and coordination. For toddlers, accuracy is not very important. The planning and coordination involved with standing or walking, lifting one foot, and balancing enough to make the foot strike the ball is a lot for a young child to accomplish. This does not need to happen in the scope of an organized soccer team and these balls are light enough that they can be kicked down a long hallway or outside in the yard. Small bins or buckets can make good targets for the ball in order to build accuracy.
For preschoolers, put small obstacles in their path and let them problems solve how to get around them for cognitive learning.
For all kids, cheering for them after each kick and taking turns kicking teaches social-emotional skills. Finally, to encourage adaptive skills, have them put the ball away when done playing.
For younger kids, throwing with two hands is also a good way to develop strength and coordination.
For infants, letting them feel, squeeze, and mouth the ball provides good sensory input. Make sure the ball is large enough to not be a choking hazard. While they are holding the ball, repeating the word “ball” to them and teaching them the sign for “ball” helps build communication skills. If they like the ball, learning the sign for it will help them ask for it before they can vocalize the word.
Who knew a $1 ball could do so much?!