There is widespread evidence showing that concept maps are effective for learning. However, little is known about the effects of various concept map activities. We conducted an experiment to examine the comparative effectiveness of three concept map activities: (1) translating a complete map to a paragraph format; (2) filling in concepts in a partial map; and (3) filling in labels in a partial map. Undergraduate students enrolled in an introductory general chemistry course were randomly assigned to the three groups. Each concept map depicted the relationships between concepts on the topic of reaction enthalpy. Results showed that the map-translation group significantly outperformed the fill-in-concepts and fill-in-labels groups in conceptual understanding indicated by open-ended questions while there were no significant differences among the three groups in conceptual understanding indicated by multiple-choice questions.