A technique for using highlighter ink as an ultraviolet dosimeter has been developed for use by secondary school students. The technique requires the students to measure the percentage of colour fading in ink drawn onto strips of paper that have been exposed to sunlight, which can be calibrated to measurements of the ultraviolet irradiance using an inexpensive and readily available pocket-sized meter. The concepts introduced in the article provide students with simple computer image processing and scientific measurement skills that enhance understanding of the ultraviolet environment. The methods presented in this article allow school students to make accurate measurements of personal ultraviolet exposure using self made and calibrated ultraviolet dosimeters which until now have not been readily available to schools. (Contains 2 tables and 3 figures.)