As reported by the Washington Examiner this week, Maryland schools must “integrate a thorough environmental education program into their pre-kindergarten through 12th-grade classes, according to a unanimous state board ruling.”

It’s certainly valid to debate the merits of green education – there’s been a lot written about it from both sides – but for now, let’s set that aside and talk about the green that really matters to schools: money. So far, Maryland’s education system has avoided the axe – but how long can that last?

In 2010, the state of Maryland faced a deficit of $2 billion, and looking ahead, problems are likely to persist into fiscal years 2011 and 2012. Even though Maryland’s Board of Revenue Estimates recently indicated that the state had taken in more revenue for the past two months than anticipated, the fact remains that massive structural problems exist across the board, from overspending to bloated state agencies to looming pension costs. The American Legislative Exchange Council’s annual “Rich States, Poor States” index ranks Maryland at 20th for economic performance, yet the state falls 29th for economic outlook.

To be sure, Maryland schools are good – Education Week named it number one in the nation for quality, and the state won a Race to the Top grant. But what does being a good system really mean when state schools are top performers in only some of their core curriculum? According to data from the Department of Education, Maryland’s math and reading scores are slightly better than the national average, while its average scores on science and writing mirror the nation’s test scores. And it’s important to bear in mind that high-performing (and high-population) districts can offset some of the low-performing districts elsewhere – so the state’s perceived “excellence” is far from universal.

Like it or not, children’s time in school is a zero-sum equation – meaning that the more time students spend on subjects like “ecosystems, natural resources and health,” and “examining ‘how their personal and collective actions affect the sustainability’ of ecological, economic, political and social systems,” the less time they’re spending learning reading, writing, and arithmetic. The same rule applies to finite education resources: the more money school districts spend on green education, the less they’re spending elsewhere. And in the process, those top results might not be the best in the country for very long.

For some parents, offering green education at the expense of focusing on core curriculum might be fine – but for many other parents, it might not be. Unfortunately for families, however, the State Board of Education has already made that choice for them.