From the website:
"Just for Kids" - Desert Scavenger Hunt - Usery Park
Usery Mountain Regional Park
Join Ranger B on this exciting scavenger hunt as we solve riddles and find things in our desert (using our eyes only). Not only will we have a lot of fun but we will also learn amazing things about our desert plants and animals! Free posters will be given to the top five winners. The 1-mile Merkle Trail offers universal access and the hard-smooth surface of this trail will accommodate wheelchairs and strollers. Please bring water and closed-toe shoes. Location: Meet at Area 6.
Time: 10:00 AM Registration Required: No Fee: $6.00 per car https://www.maricopa.gov/parks/usery/EventsDetailPublishers.aspx?date=3/16/2014&EventID=21103