In this article, we describe and evaluate a Web-based interactive tutorial used to present hypothesis testing concepts. The tutorial includes multiple-choice questions with feedback, an interactive applet that allows students to draw samples and evaluate null hypotheses, and follow-up questions suitable for grading. Students either used the interactive tutorial (n = 15) or completed a standard laboratory assignment (n = 10) covering the same topics. Students who used the tutorial performed better (p = 0.06) on a quiz than students who completed the standard laboratory, supporting the effectiveness of this freely available online tutorial. A second group of students (n = 112) who did not participate in the assessment overwhelmingly rated the tutorial as easy to use, clear, and useful.