There is a need to evaluate the benefits to children of integrated classroom and field-based learning. In this article, we describe a case study that involves children in the production of a field guide: an authentic task which integrates learner autonomy and open enquiry with field work, information and communication technologies (ICT) and classroom-based activities. We consider the impact that this task has had upon aspects of the children's factual writing. Although we found no improvement in the ability of the children to write sentences and only a marginal improvement in their ability to write for composition and effect, we did find a significant improvement in their ability to write about the ecology of an animal that they had encountered firsthand when compared to an animal that they had not encountered in life. (Contains 3 figures.)