Homeschooling is two things. One is, we bring school everywhere like the one pictured above. They brought their books with them and while waiting at the airport for the arrival of their uncle, they were reading their books there. They narrated back to me and we discussed their lesson. Which is quite similar to what happens when we "homeschool" at home.
The other thing is when we go to a place of discovery. That place could be a museum, in a beach, in a manufacturing plant, at the foot of a volcano, at the backyard, at the grocery store or even while travelling in a car. When you've been homeschooling for a while, it becomes a lifestyle. You could find something to teach your kids and learn about, everywhere. My kids would often copy me and say, "We're homeschooling, guys!"