In the beginning animation you learn that there was a significant warming period about 10 million years after the dinosaurs went extinct. This warming can be seen
in the fossils of leaves from that period. In the activity we are determining how
many leaves are "toothed" rather than smooth. From the animation, what do they
say is the advantage to leaves being "toothed", what does it allow them to do?
You

the principles and empirical processes of discovery and demonstration considered characteristic of or necessary for scientific investigation, generally involving the observation of phenomena, the formulation of a hypothesis concerning the phenomena, experimentation to test the hypothesis, and development of a conclusion that confirms, rejects, or modifies the hypothesis.

it's diluted or concentrated

in a diluted solution, you can add a lot more solute but in concentrated only a little more can be added