The study of flower structure is essential to understanding sexual reproduction in plants, pollination syndromes, plant breeding, fruit structure and identifying plants. Thus the study of flower structure, and the construction of floral formulae, are a standard part of first year university botany or biology courses. These activities involve developing a complex set of skills and it is useful for students to be able to review this material after practical sessions. The "Virtual Floral Formula" website provides students with a unique resource for practicing their floral structure interpretation skills. The website provides detailed dissection photographs of the flowers of 12 species and floral formulae are progressively assembled via drop-down menus. When students are satisfied with their answer it is submitted and any discrepancies from the "official" formula are then highlighted. Students appreciate the interactivity of the application, the feedback they receive on any inaccuracies in their formulae and the ability to make progressive improvements in their skills.