To fake sick and hopefully stay home from school try waking up before your parents do and fake like you're vomiting.
Also moan and groan in bed and try heating a thermometer up by using some hot water but just don't make the thermometer read too high of a reading otherwise you'll be found out.
When you're supposed to get dressed act fatigued and take your time getting dressed and be reluctant and act like you're dizzy.
If your parents still insist you go to school don't act excited but instead protest against it and your parents may let you stay home from school.
After faking sick you'll need to stay in your room and in bed at least during the time when your parents are home.
If they go to work and you get up out of bed make sure you return to bed before they get home.