You're right. Summer is more than six weeks away.
Summer begins 6/21/19.
Today is May 8, 2019.
Number of days including start and end dates: 46 days.
46÷7= six weeks plus four days.
No. Public schools (which private school requirments mimic, not necessarily copy) have been required to provide at least 180 days of education, for at least the last 50 years. Common Core went into effect in 2009. There are no "extra" days in the typical school year for Common Core instruction or testing.
Just for general information, a private school operating only 160 days a year is cheating its students, along with whoever is paying tuition, if it offers less than six hours and 12 minutes of classroom time daily.