Since 2017, HeatQuiz is developed as a tool for students in the subject of Heat and Mass Transfer to train their skills and strengthen their knowledge. The topics span from view factors to temperature distributions up to dimensionless numbers. With more that 800 questions, HeatQuiz provides a large variety of questions in it's database. Due to the COVID-19 pandemic and the obligation for social distancing HeatQuiz has evolved from a mobile teaching application with customized subject-specific question types to a tool that combines game-based elements with structured access to an open heat transfer lecture. Combining micro-lectures for the flipped-classroom concept and hundreds of quiz questions in a well structured learning environment is one of the main strengths. This article describes the learning path concept and how it is embedded in HeatQuiz. Secondly, a new question type will be introduced that is especially designed to practise the skill of developing energy balances based on a sketch of the control volume, defining all relevant fluxes, and finally defining the required boundary conditions.