What to do with kids that are different ages?

I would like some advice about the age differences between my kids. I have a 10 and a 3 year old. I find it difficult to come up with activities to do with both of them. Summer is coming and I am a little worried about this. If we play a game, my 3 year old either has to sit out or my 10 year old has to play a 3 year old's game. My 3 year old has grown out of the bike seat so I'm not sure how to go for bike rides with my 10 year old anymore. Activities that my 10 year old enjoys, my 3 year old does not have the attention span to sit through.

I personally have loved the age difference so far. I liked having a break from diapers, etc. before having another one. But the 'what to do with them both now' question is really puzzling me. Any help would be appreciated.

hmmm... that's a hard one because 3 year olds aren't too developed yet :)
But- I can think of a couple things... What about swimming? Taking them to the community pool or turning on the sprinklers in the back yard.
Or you could do physical activities with them, such as having the 10 years old teach the 3 year old how to hit a baseball or play catch. That would be a bonding moment and something fun for both of them.

There is no reason a 3 year old can't ride their own bike. You just might need to go slower. My sister and I are 12 years apart in age and we went to the park, went swimming, roller skating, fishing, there are tons of things to do. A 3 year old is capable of doing many things a ten year old can-just slower.