Mass is the amount of matter in any object.
What this student is doing is collecting data. So, he wants to check how many life forms there are in the waters nearby. In order to do so, he has to take a sample, and look at it through a microscope so as to determine the number. So, he collected a sample which is his data. He is not drawing conclusions yet, but rather counting these organisms. He is not making a peer review - his peers aren't even mentioned here. He is not forming a hypothesis because he is just counting at this point.
A vaccine works by training the immune system to recognize and combat pathogens, either viruses or bacteria.
Episodic Memory!
Episodic memory includes personal information on what happened and where.
Hope this helps!
