When all of this is looked after, get out the TOYS, the more the better. Best are trucks and cars, shovels and pails, doll buggies, plastic mud molds, even a trike or other ride-ables if you have the space and no stairs or steep inclines. The closer to the ground the toys, the safer their users. Remember too, sidewalk chalk washes off easily. Spreading cheap foam exercise mats on concrete surfaces not only save scrapes but provides another colorful play surface.
Sand boxes are great.
Make sure yours has a cover to keep off the rain and, especially, to keep out the critters, which love them for basic toileting. The formed plastic sand boxes are best. They come with lids light enough for toddlers to remove and replace. Figure on half of the sand being outside the box at any given time. Sift this as you put it back in the box because it may contain yard debris.