Activity-Based Tutorials are a set of small-group, guided inquiry learning materials designed for use in recitation and discussion sections.  Students develop conceptual knowledge of the physics through: simple experiments using computer data acquisition tools, basic observations enhanced by the use of digitized videotape of real phenomena, analysis of computer simulations that aid in visualization of abstract ideas conceptually rich problems. The Activity-Based Tutorials are designed to accompany and enhance lecture instruction. They have been developed using a cycle of physics education research, including investigations into student learning on a given topic, development, and revision of the materials based on evaluation after use in the classroom. In Activity-Based Tutorials Volume 2: Modern Physics, tutorials exist for topics in probability, quantum tunneling, and conductivity.  Activity-Based Tutorials are a component of the Physics Suite.  The Physics Suite is a collection of materials created by a group of curriculum developers and educational reformers known as the Activity Based Physics Group.  The Physics Suite contains a broad array of curricular materials that are based on physics education research.