The Next Generation Science Standards encourage students to develop the reasoning and practice skills of scientists. Rather than promoting rote memorization, teachers engage students with real-world phenomena and prompt students to think critically. ChemVLab+ is a series of freely available, online modules that require students to reason like "chemists" by integrating core concepts with investigations in authentic contexts. Each activity reflects four key design principles as well as a novel framework for developing chemical reasoning specific to the practice of designing and interpreting experiments. The current paper describes the development and testing of the ChemVLab+ modules. A within-teacher randomized control trial study (treatment = 15 class sections with 371 students; control 14 class sections with 332 students) found that students using the ChemVLab+ modules outperformed students completing a set of active control modules that offered a more traditional instructional approach and problem-solving opportunities. ChemVLab+ students scored higher than their active control peers on 7 of 8 module quizzes and performed particularly well on open-ended response items that were focused on chemical reasoning for experiments. Analyses of demographic effects also revealed a positive interaction between BIPOC students and the ChemVLab+ intervention.