When looking for an outdoor activity to do with your kids, I recommend building a fairy house.  It is so much fun and can basically be made anywhere with anything natural.  To start out, look around your yard or wherever you may be for pieces of wood, bark, flowers, rocks, shells, pinecones, acorns,etc. and then find a place to prop up your objects and make a cozy little den for your "fairies".  We always add little furniture inside by putting a flat rock or branch and pretend they are sofas, tables, chairs, beds, etc...  It's also fun to give them some food like:  pieces of flowers, seeds and acorns.  My kids have a lot of fun even though they are boys and the oldest is almost 3.   There is also a fairy festival coming up this coming weekend in Portsmouth that looks like a lot of fun!