This document discusses context-based mobile learning. It defines context as that which surrounds us and is constructed through interactions. Three projects are described: CAGE used location-based content on handhelds in a museum; MyArtSpace connected museum visits and classrooms via student-created multimedia on phones; PaSAT used location-based games on PDAs to support learning outdoors. Results showed these approaches engaged students, supported inquiry learning, and connected formal/informal settings, though more teacher preparation and classroom connection were needed. Creating temporary "islands" of stable context is important for mobile learning.