list the 5 different ways an "informal amendment" can be made to the constitution?

Answer 1

1. No way
2. No how
3. Can't happen
4. Huh?
5. What are you talking about?

There are only two ways to amend the US Constitution. Neither is 'informal'. See Article V below.

The Congress, whenever two thirds of both houses shall deem it necessary, shall propose amendments to this Constitution, or, on the application of the legislatures of two thirds of the several states, shall call a convention for proposing amendments, which, in either case, shall be valid to all intents and purposes, as part of this Constitution, when ratified by the legislatures of three fourths of the several states, or by conventions in three fourths thereof, as the one or the other mode of ratification may be proposed by the Congress; provided that no amendment which may be made prior to the year one thousand eight hundred and eight shall in any manner affect the first and fourth clauses in the ninth section of the first article; and that no state, without its consent, shall be deprived of its equal suffrage in the Senate.

Answer 2

Let's see there is

Court opinion such as Roe v Wade

Practical usage. The Congress cap the House of Reps contrary to the Constitutional rule for one per 20,000 or so.

Presidential assumption of powers. We can now have undeclared wars when this is soley the right of Congress.

Congressional assumption of power. Congress passes laws that violate the 10th amendment every day using the interstate commerce clause.

I can't think of a case that doesn't fit one of these