This kit is a unique teaching tool for introducing your students to the fascinating chemistry and physics behind invisible inks, i.e. colorless substances usable for writing that can be made to run color using a chemical or physical process. Students investigate how organic fluids and chemical reagents can be used as invisible inks. Relying on historical example, students create various invisible inks and security documents for other student groups to analyze and decode! Includes materials for two detailed activities (each with a 'model' and 'inquiry' investigation paths - a total of four investigational activities), which can accommodate up to 40 students. Also contains a DVD with PDF Teacher and Student Guides and other digital content. Covered concepts include: data analysis, chemical and physical processes, elements, mixtures and compounds, pH indicators, transmitted vs. reflected light, the periodic table, fluorescent compounds, types of chemical reactions, and hypothesis testing.