There's 104 days of summer vacation
And school comes along just to end it
So the annual problem for our generation
Is finding a good way to spend it
In the title sequence, we see the calendar starting at June 3. 104 days later would be September 15. Over 3 months.
What school do they attend that they get such a long summer vacation?
"Mom, Phineas and Ferb are making a title sequence!"