Was Jesus in the grave 3 days and 3 nights?
Actually, according to scripture, He was.(Matt 12:40). Problem is, as noted, we can't squeeze three days and three nights in between "Good Friday" and Easter Sunday morning. Here is another example of tradition vs. truth. Throw away the Friday tradition, and your problem is solved. Jesus was crucified on Wednesday, not Friday. That particular Wednesday turns out -- from a study of the calendar -- to have been the passover day in that particular year. So the Jonah parable fits perfectly!
God bless you and yours