Experiment with mass and density as scholars figure out what makes things float or sink. First, they watch a podcast introducing these concepts. Be sure to use the comprehension question to test their understanding. Young scientists complete a virtual lab which may not function based on your computer's updates. Consider conducting an actual lab using this concept. There is a handout for them to organize findings and determine whether or not there is a correlation between mass and floating. Find a 10-question worksheet linked here to give scholars some independent practice. There is also a hot air balloon word problem link, which lends itself well to an all-class practice problem.