Decisions on introducing questions that address new topics within themes will be informed by reflections on recent research literature, or by interests expressed by TALIS participants, often in relation to prior TALIS findings. The inclusion of core questions held constant for the purpose of time-series analyses will reflect the indicators that education systems still prioritise as key indicators of how well they are functioning. The TALIS conceptual framework serves to structure the constructs and instruments in a way that facilitates decisions on which constructs and measures to include in TALIS 2018.