This paper focuses on describing a teaching activity aimed at exploring the use of translation as a teaching and assessment tool in English as a second language classes and as a means of improving teachers' planning and educational practices. The proposal is divided into two activities using different translation concepts. The first involves the development of an activity based on what Jakobson (2004, original work published in 1959) called intersemiotic translation or transmutation, i.e., the process of translating between a verbal sign system and a non-verbal one. This activity, which was completed by third-year primary school students, is based around producing a symmetrical transmutation from text into illustration. Its main objective is to improve and assess reading comprehension skills by using a motivational and innovative approach. The second action focuses on analysing the results using translational criteria. Given that there are similarities between translation and illustration, which scholars like Pereira (2008) have noted, the drawings crafted by the students are assessed using different traditional procedures from translation studies as assessment criteria, such as Hurtado Albir's (2001) literal translation and amplification and Vazquez Ayora's (1977) explicitation, among others. The experience as a whole has revealed interesting results in both aspects. On the one hand, it has shown how concepts from the field of translation can be a useful tool for evaluating the right and wrong decisions students make when carrying out this type of activity. On the other, the fact that this assessment mechanism enables teachers to identify the knowledge acquired in order to analyse and improve their own teaching practice, adapting it to their students' learning needs has been confirmed.