Two groups of middle school students were taught U.S. colonial history during a 5-week period using 2 different instructional strategies. In the experimental group, concepts and problem-solving strategies were explicitly taught; in the control group, content was presented using lectures and reading. All students took a pretest and several posttests. Declarative knowledge tasks measured factual content knowledge and domain vocabulary acquisition; procedural knowledge was measured with problem-solving essays. Whereas performance was not statistically different between the 2 groups on the fact tests, significant differences were found on the vocabulary tests and problem-solving essays. These findings support using direct instruction for relational thinking and problem solving with explicit reference to concepts and attributes.