As highlighted by the National Math Panel Report (2008), consistent results from laboratory studies have demonstrated that interleaving worked examples with problems to solve improves learning for novices. The purpose of this work is to create materials and tests that can be used flexibly in classrooms and which employ worked examples interleaved with practice problems for students to solve. A total of 42 assignments addressing some pre-Algebra and 8 major Algebra topics have been developed through an iterative process. The effects of AlgebraByExample on learning has also been explored with particular attention to the role of individual differences. The eight participating districts are all members of the Minority Student Achievement Network (MSAN) which is a self-formed alliance dedicated to addressing the achievement gap: Ann Arbor (MI), Arlington (VA), Chapel Hill--Carrboro City (NC), Evanston Township (IL), Evanston/Skokie 65 (IL), Green Bay (WI), Shaker Heights (OH), and Madison Metropolitan School District (WI). Although this paper does not cover all of the individual studies, the body of work as a whole has been conducted in 300 classrooms with over 6000 7th-10th graders, with the majority of 8th or 9th graders enrolled in "regular" Algebra. Approximately half of the students in each participating class were randomly assigned to the example-based group, in which they received the example-based assignments designed for the study. The other half was randomly assigned to the control group, in which they received an alternate version of the assignments that contained the same types of problems, but no examples or self-explanation prompts. Results demonstrate that students in high-minority populations benefit more from example-based assignments than do those in lower-minority groups in terms of an increase in their procedural performance. Results also indicate that conceptual learning occurs more readily for students in low-minority classrooms -- students in higher-minority classrooms do not tend to learn as much. However, for students in high-minority classrooms, being in the example-based condition leads to greater learning than the control condition. One table and two figures are appended.