You'll be surprised what you can find out about what's going on with them

How’s life?
When they were very small I'd get odd responses like "stinky" or "hot". Now that they're a little more grown up I am getting somewhere with it. It's a good opportunity for them to tell me something that's on the tip of their tongues that they might not have divulged had I not asked. The timing sometimes has to be just right to get something juicy or paramount. I don't press them to answer though, if they need to talk, this question lead them to an opportunity to open up.
How are you getting on with your friends?
Sometimes I am more direct and will ask about a particular pal especially if know there's something going on in the family home, or if my kid has not been getting along so well with someone. Mostly I keep it generic and just ask about their mates in general. Watch what happens when you direct the attention away from them and shine the light on their friends. Chances are, your son or daughter will be more likely to chat.
Anything interesting going on?
Sometimes, I forget about things coming up, and if I pop this bad boy out, they'll usually remind me of it. But sometimes I'll get info on something that they're really interested in and it can be the basis for a treat or reward for good behaviour. It's lovely to surprise them.
Can I help with anything?
By asking this my kids know I’m there for them when they needs me. Sometimes for little people, it can be tough for them to ask for our help so I offer it up. Mostly I get a na/no/nope or I'm ok but sometimes I get to help them out and it's a nice bonding experience for both of us. I'm prepared for the day when the help may extend beyond homework or cleaning their room, but the ground work will have been done at that stage hopefully and it will mean that they will never be afraid that I'll not help them when they really need it. 
These four questions keep the banter and the chat going between my kids and I and it keeps my husband and I up to date with what's going on in their lives. Long may it last x