Easily? Based on what? Who? Maybe you're right. Maybe its the only private HS in JC. Wasnt my experience at all in Pvte School.
Well public school is also very right leaning, at least in TN. Just thinking back to growing up we learned Columbus was a saint, manifest destiny was good, read 1984, Ayn Rand, everything about unfettered market capitalism and nothing about the triple bottom line or other ideas, read other right leaning novels, never even heard of Howard Zinn's "A People's History of the United States" until college, all the founders were traditional Christians and not that some were rational theists or deists (didn't even teach us deism), etc. At best we read a few paragraphs about Upton Siclair's work. We didn't read it though. That's about as far left as I remember anything being taught. Fwiw this was Knox County.
Fwiw not saying the above books weren't really good and shouldn't be taught, but there was zero balance. A lot of one side. Which is why I also think a lot of people think college can be left-leaning, because at that point a bit of left-leaning material can be shocking to most of us that learned one viewpoint growing up. I remember realizing how closeted I was just one semester into college and that was ETSU, not exactly a bastion of liberal thought lol.