School lunch changed this year. Here is what is actually different on the tray.

New nutrition standards took effect with the school year. Most of the coverage has focused on what is being removed. What is on the tray is a smaller change than either supporters or critics have suggested, and the practical obstacle is not the standard at all.

The added sugar limits apply first to the categories where most of it sits: breakfast cereals, yogurt and flavored milk. A sodium reduction of about 15 percent phases in over three years, deliberately slowly, so that recipes and supplier contracts can be reworked rather than replaced.

The kitchens are the problem

In a survey of 480 districts, two-thirds named equipment as the binding constraint. Meeting the standards generally means preparing more food on site rather than reheating pre-prepared items, and a large share of school kitchens were built or renovated for reheating.

A kitchen with a warming cabinet and no working oven cannot roast vegetables regardless of what the standard requires. Districts in that position are meeting the letter of the rules with cold preparations, which is compliant and not what anyone intended.

Everybody wants scratch cooking. Scratch cooking needs a stove, a hood, a walk-in and someone trained to use them. We have one of the four.— A district food service director

What children actually eat

Plate waste studies from districts that made the change early are encouraging in one respect and sobering in another. Overall waste did not increase, which addresses the most common objection. But the share of students taking a school lunch at all fell slightly in high schools, where students can leave campus.

The districts with the best results did the same two things: they changed one item at a time rather than the whole menu, and they let students taste and vote before a new item entered the rotation.

• First limits: added sugar in breakfast cereals, yogurt and flavored milk
• Sodium: about a 15% reduction phased over three years
• Constraint: two-thirds of 480 districts surveyed cite kitchen equipment
• Plate waste: unchanged overall; high school participation slightly lower

For parents, the useful thing to know is that the published menu is now more likely to match what is served, because the standards require the district to post the actual recipe rather than a category. If a school posts a menu it cannot cook, that is visible in a way it was not before.