Inverse and injective functions are topics in most college algebra courses. Yet, current materials and course structures may not afford students' conceptual understanding of these important ideas. We describe how students' work with digital activities, "techtivities," linking two different looking graphs that represent relationships between variables in the same dynamic situation, can help to address this problem. To bolster our argument, we provide empirical data from a broader study, drawing on student work and instructor interviews across three institutions. We conclude with illustrations of how techtivities can serve as instructional anchors for injective and inverse functions.