Mobile technologies are increasingly being promoted as tools to enhance learning. They can be used to augment ongoing activities, such as exploring outdoors, by enabling users to move back and forth between the physical environment and a variety of digital resources and representations. In so doing, they have the potential to facilitate sensemaking activities, where people seek to find structure in an uncertain situation through using a combination of information, communication and computation. However, continuous switching of attention between different representations and activities can be distracting. Our research is concerned with how mobile devices can be used to engender collaborative sensemaking activities during scientific tasks. We present two studies showing how different versions of a mobile learning application, LillyPad, were used by teams to make sense of their ongoing observations, when measuring the effects of different planting methods for an environmental restoration site. The findings show marked differences in the amount and type of sensemaking. We discuss reasons for this in terms of task demands and workload, information type and distribution of devices.