I posted about in another comment, but can’t find it.
Personally I think I have always managed to apply inquiry based learning to sinking and floating with good outcomes. There is so much scope for this topic and children always love it because what they deem as playing with water is actually embedded in so much learning opportunities. To start we would identify items we would like to test out and have a discussion around whether they will float or sink. Including lots of related vocabulary to build understanding and drawing on their prior knowledge. I like to link it into swimming as the children I teach go swimming for the first time in first class. Within the learning the children explore, wonder, predict and reason what will happen to each object. I love the discussions the children engage in with each other and how they communicate their understanding to each other. The children love to then test out and draw conclusions. I often find children will go home and test further items out and will be so excited to share with their peers the next day.