The use of manipulatives in the classroom has been advocated for decades. However, the theoretical and empirical support for this practice is mixed. Some researchers suggest that manipulatives facilitate learning by (a) providing an additional channel for conveying information, (b) activating real-world knowledge, and/or (c) improving memory through physical action. However, there are at least two reasons to question the efficacy of manipulative use. First, manipulatives might lead students to focus on having fun at the expense of deep learning. Second, manipulatives might make learning more difficult because they require dual representation. Although these two criticisms are disparate in terms of their underlying rationale, both converge on the idea that teachers should reduce their use of manipulatives that are highly familiar and/or perceptually interesting. More generally, the manipulatives debate highlights the need for teachers and researchers to work together to evaluate the costs and benefits of various classroom practices.