Debbie was doing a science lab, and she was instructed to decide whether a piece of plastic would float or sink without actually putting the plastic in the water. how could she do this?

Determine how heavy the piece of plastic is and if it's light than it is most likely to float

She could do this because of the density level in the water and the density of the plastic. If the density of the plastic is lighter then the water then it will float but if it is heavier then it will sink.

Size and shape of continents