"I've never heard of a small speck of dust that is able to yell" says Horton of a sound he hears well (Geisel 1954). It is always valuable to connect science to student's interests and their everyday world--so what better way to teach concepts relating to sound than to read "Horton Hears a Who" by Dr. Seuss? Here the authors present several activities that can be integrated with this timeless story, in which students use the process of scientific investigation, such as asking questions, forming a hypothesis, testing ideas, analyzing data, forming conclusions, and communicating results. (Contains 3 online resources.)