DIY Sand and Rock Box by FSPDT. Gdjk -> made this with toilet rolls (aka tunnels) and moon sand instead of play sand. My son loved playing with it. The moon sand cleans up nicely indoors but play sand will be easier to play with when using the small cars.
Make some footprints on playdough or identify an animal from its footprint Try to keep them in natural groupings (by species like birds/insects/reptiles, by geographical location Australia/Africa/America or by type pets/farm/zoo)