Based on four published articles on Swedish upper secondary school pupils’ use of online resources during essay writing in Spanish L3, this thesis in educational work and Romance languages focuses, from a language education perspective, on the use of machine translation. Two of the articles observe pupils’ use of online resources in general, and of Google Translate in particular, revealing a complex weave of strategies where Swedish, Spanish, and English are used to search, change and control word sequences, simultaneously including lexical, morphological, and syntactic aspects of the languages. The other articles study the effects of machine translation on text length and on lexical, morphological, and syntactic accuracy and complexity, as compared to texts written with printed dictionaries as the only translation tool. The results point to small but statistically significant positive and negative effects on complexity and accuracy. As for effects on vocabulary, the use of machine translation is shown to increase lexical diversity as long as it remains in use, the effect, however, vanishing when the tool is no longer utilised.

In the introductory chapters of the thesis, the results from the articles are re-analysed from a Gibsonian ecological affordance perspective, focusing on the pupils’ explorative and performative interactions with the affordances of machine translation, and on the pupils’ strengths and challenges when handling the Spanish language.

The thesis contributes to a deepened understanding of the complexity of foreign language learners’ interactions with machine translation, and further points to the importance of strengthening (meta-)linguistic awareness, linguistic self-confidence, and technological know-how in foreign language education. The thesis also underscores the importance of language teachers’ taking an active part in reinforcing the above-mentioned areas, and raises key questions about the future of writing in foreign language education.