Continent Or Not

This evening a really interesting question was asked...."what qualifies a landmass as a continent?" As homeschoolers, I encourage my kids to use the resources available to them in order to answer their questions, but the answer to this seemed illusive. I expected a very clear set of standards to set continents apart from other landmasses but I was disappointed. Apparently there is no consensus about what qualifies and children in other countries are taught differing numbers of continents....varying from 4-7. I'd love to hear your input.

What qualifies and landmass as a continent and how many continents were you taught there are?