During my four years as a teacher student I have identified a lack within pupils’ conceptual understanding of the English language. Teachers in grade 4-6 often work with weekly vocabulary tests regardless of their inadequacy. Therefore, the purpose of this study is to contribute with a development project that elaborates pupils’ conceptual understanding of English words. This project focuses on the pedagogical method of concept definition maps. During the study’s intervention the pupils discuss English concepts by translating them, defining them, providing facts about them and constructing example sentences. The study will therefore focus on the pupils’ perspectives and their experiences. Furthermore, the study will answer questions about how concept definition maps can promote pupils’ understanding of concepts in English, and what differences pupils experience when they work with vocabulary test versus concept definition maps. The questions are answered by way of two qualitative methods, classroom observations and interviews with pupils. The purpose of the observations is to answer the first question of the study by examining the pupils’ work with the concept definition maps, and the interviews are aimed to answer the second question. Furthermore, the study’s theory is based on Lev Vygotsky’s sociocultural perspective that supposes that learning is a social and cultural process. The study also focuses on the concepts of appropriation, interaction and contextualization. The result confirms that the vocabulary tests in today’s schools need a form of development and continued planning. The concept definition maps were considered useful because the pupils were able the develop both their oral and written language skills. The result also showed that the pupils made their own definitions of certain words by linking them to their past experiences and everyday life. The pupils also supported each other which contributed to deepened conceptual understanding.