I've been a grandmother since 2003. Oh ya they are little tape recorders.
I take care of them while my daughter works during the summer. They ask endless questions. And I've always answered them honestly (albeit age appropriate answers).
We spend most of our time outside. Yesterday we loaded up on the Polaris Wheeler and did a sojourn into the woods.
Learning about all the plants (I'm a forager).
They both love hunting for turtles and frogs. I've been trying to find a slider for a pet them.
Pretty soon the 8 yr old will be ready to drive her machine into the woods with me.
Nice. Get them outside as much as you can. I have four grandkids. Two of them are 'inside cats' for the most part. The other two are living with us right now (and our daughter), one is 3 months old, but the three year old loves to be outside getting into things. Likes to check out the plants, pick some raspberries off the plant and eat them, and run around.
Keeping them off the keyboards and outside is the best thing you can do for them, for education and health.