Redlands Conservancy. This one is a kid-centric event featuring "demonstrations, activities, hikes, lunch - free and open to the public."
It doesn't say there, but a little bird tells me Mr. Friis is organizing bike rides for the kiddos that come down with them. Faithful readers may recall the recent trail clean up and goathead reduction day held there. Don't want kiddos riding around getting lots of flats!
Be sure to register at (909) 792-1800. That way you can get lunch, which is usually not to be missed (hopefully from Oscars!).