TASK DEFINITION: Given scientific fact as input, generate the question from this fact such that it can be answered from the input.
PROBLEM: The values of strangeness assigned to various particles are based on decay systematics.

SOLUTION: The values of strangeness assigned to various particles are based on what?

PROBLEM: Mesoderm type of cell layer do flatworms have.

SOLUTION: What type of cell layer do flatworms have?

PROBLEM: Three many families are known quarks divided into.

SOLUTION:
How many families are known quarks divided into?