This paper is a comparative quantitative evaluation of an approach to teaching poetry in the subject domain of English that employs a "guided discovery" pedagogy using computer-based microworlds. It uses a quasi-experimental design in order to measure performance gains in computational thinking and poetic thinking following a microworld-based intervention in English lessons. Preliminary findings reveal a distinct increase in computational thinking and poetic thinking performance for learners who participated in the intervention. There is also some evidence, though this requires further research, to suggest a relationship between high performance in computational thinking and high performance in poetic thinking.