Below is the mathematical practice for career and college ready standards.
Construct viable arguments.
Mathematically proficient students understand and use stated assumptions,
definitions and previously established results in constructing arguments. They
make conjectures and build a logical progression of statements to explore the
truth of their conjectures. They break things down into cases and can recognize and use counterexamples. They use logic to justify their conclusions, communicate them to others and respond to the arguments of others. They reason inductively about data, making plausible arguments that take into account the context from which the data arose.