When I was in the science classroom students would come in with the "pre-lab" questions completed as homework. Then they could get started right away on the lab. If they did not have the pre-lab done they did not have time to do the lab (the fun part) during that class period.
A few years ago I was involved in a conference called #FlippinUtah. Some of the links gathered at that time are still relevant and some are gone. But the Flipped classroom is still here and will be making a comeback during COVID-19.