This article describes a laboratory module designed to help students understand how different compounds behave when they are dissolved in water. Students measure the conductivities of various aqueous solutions using handheld conductivity testers with LED displays. By counting the number of LEDs illuminated, students can differentiate between electrolytes and nonelectrolytes and approximate the relative numbers of ions in solution. This enables students to discover how ionic compounds dissociate when dissolved in water. The laboratory module introduces the model–observe–reflect–explain (MORE) thinking frame, an instructional tool that encourages students to connect their macroscopic observations with their understanding of the behavior of particles at the molecular level. These activities are designed for college-level general chemistry courses, but have also been adapted to the high-school level.