Road Trip Bingo Car Game for Kids; print it out, give each family member a card. I make them photograph the sign on their mobile phone to "prove" that they saw it ;) Littlies can get Mum or Dad to mark when they see a sign.
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.
33 Activities Under $10 That Will Keep Your Kids Busy All Summer
Balloon rockets! Easy fun activity for kids! I love the educational aspect of the experiment as well! You can explain how real rockets work by exploding fuel inside a chamber that is open at the bottom. The force of the explosion creates an opposite force that pushes the rocket up and into space. Cool!