Authentic assessment is important in formal and informal learning. Technology has the potential to be used to support the assessment of higher order skills particularly with respect to real life tasks. In particular, the use of mobile devices allows the learner to increase her interactions with physical objects, various environments (indoors and outdoors spaces), augmented digital information and with peers. Those interactions can be monitored and automatically assessed in a way that is similar to traditional objective tests. However, in order to facilitate a meaningful interaction with formative purposes, we propose that the assessment process can be assisted through scaffolding mechanisms that transform the mobile system into a "more capable peer". In this context, this paper presents the m-AssIST model which captures the necessary emergent properties to design and analyse m-assessment activities. The model is used to analyse the benefits and limitations of existing m-test based systems. This paper discusses the importance of meaningful interactions, and the provision of scaffolding mechanisms to support formative and authentic assessment.