The primary purpose of the present study is to compare the effectiveness of the jigsaw task and information gap tasks in understanding new words and retaining them. Sixteen pupils aged between eleven and twelve were involved in the study and divided into two groups. They were allocated either a jigsaw task or an information gap task. This study consists of a pre-test, immediate post-test, delayed post-test as well as a questionnaire. The pupils were required to carry out the chosen tasks, tested immediately and then one week later. The results of the questionnaire are also discussed in order to establish the pupils’ attitudes towards their allotted tasks.   The results revealed marginally higher scores in the immediate post-test for pupils performing the information gap task in terms of recognizing the meaning of words. However, this advantage disappeared when it came to the depth of vocabulary knowledge and word meaning retention. Pupils performing jigsaw task outperformed group B in productive vocabulary knowledge and their retention. The gain in vocabulary among pupils who performed the jigsaw task is most evident in the delayed post-test. This result is consistent with the pupils’ assertion that they enjoyed doing the jigsaw task more than the information gap task. To sum up, the jigsaw task best promotes pupils understanding of words and their retention.