Legos

One activity which my kids love to do more than anything is play with Legos.  We have a bunch of kits, which they can assemble by following the directions.  But, most of the time they make up their own creations. 

 They will, without exaggeration, play with these for hours every single day:

Many of their creations have stories attached to them.  This is a turtle pool, with a computer monitoring the water, etc.

 This is a fashion runway, with models walking down it to show off their clothes:

I love how the kids can play with Legos for so long.  They frequently make creations which go along with what we are reading or studying, or based on some activity we just did (like the fashion runway).