Use possessive form for schools

Answer 1

The plural possessive form is schools'. Example sentence:

The board decided that all of the schools' hours would be coordinated to accommodate the number of buses available.

Answer 2

Both forms are correct:

• the word schools' is the plural possessive form (belonging to two or more schools)
• the word school's is the singular possessive form (belonging to one school)

Examples:

Our school's principal is Mr. Gray. (singular, the principle of one school)

All of the schools' principals attended the meeting. (plural, the principals of all the schools)

Answer 3

The possessive form of the noun high school is high school's.

Example: Our high school's colors are red and blue.