In partnership with both formal and informal learning institutions, researchers have been building a suite of online games, called choicelets, to serve as interactive assessments of learning skills, e.g. critical thinking or seeking feedback. Unlike more traditional assessments, which take a retrospective, knowledge-based view of learning, choicelets take a prospective, process-based view and focus on students' choices as they attempt to solve a challenge. The multi-level challenges are designed to allow for players' "free choice" as they explore and learn how to solve the challenge. The system provides them with various learning resources, and tracks whether, what, how, and when they choose to learn. This paper briefly describes a partner's curriculum focused on data literacy and visualization, the design of a choice-based assessment for their program, and reports on an initial study of the curriculum and game with 10th grade biology students. Results are presented in the context of the design research questions: "Do student choices in the game predict their learning from the game?" "Does the curriculum teach the students to choose more effectively with respect to data visualization?" Future work for choice-based assessments is also discussed.