1. Explain it simply
Take the verb and say it twice with 不 between: 去不去, 是不是, 要不要.
This asks a yes-no question, so you do NOT add 吗.
有 is special: it uses 没, giving 有没有.
Adjectives work the same way: 热不热, 忙不忙.
2. Show examples
你去不去学校？
Nǐ qù bu qù xuéxiào?
Are you going to school?
verb 去 → 去不去
你有没有妹妹？
Nǐ yǒu méi yǒu mèimei?
Do you have a younger sister?
有 uses 没
今天热不热？
Jīntiān rè bu rè?
Is it hot today?
adjective 热 → 热不热
3. Share a tip
A V不V question already asks yes-or-no, so never add 吗. Two-syllable verbs can shorten: 喜欢 → 喜不喜欢.