This article develops Kress and Van Leeuwen's insight that material features combine with visual and linguistic features to convey meaning, showing how this is particularly true of the meaning-making practices of children. Taking examples from a corpus of project work by children aged 8-11 years, we identify the sorts of material resources they were drawing on and categorize the examples according to the types of meaning they carry, linking this categorization to Halliday's three macro-functions of semiotic resources. We then provide examples of the ways in which physical characteristics provide traces of decision-making processes in the construction of a meaningful message, and of importation and adaptation of semiotic material from elsewhere. We end by suggesting that the practices we have observed represent a fast-changing period in the development of technologies of literacy and that awareness of the materiality of children's meaning making may contribute to an understanding of the richness and complexity of literacy development.