Understanding time-dependent responses, such as transients, is important in electric circuit theory and other branches of engineering. However, transient response is considered difficult to learn since familiarity with advanced mathematical tools such as Laplace transforms is required. Here, we analyse and describe a novel learning environment design, the problem-solving lab, for learning transient response. This design merges problem-solving classes and labs, allowing students to engage in deep learning through the integrated use of tools like paper and pencil, MATLAB[R], simulations, and experiments. A key element in this design is the systematic use of variation in line with variation theory. We describe critical features for learning transient response, and ways to facilitate the establishment of links between the 'worlds' of theories/models and objects/events for students. We contend that an integrated use of tools, and systematic use of variation, is crucial for learning and establishing these links. (Contains 1 note, 5 tables and 5 figures.)