Ziploc baggies and foil-lined juice boxes are out.

Cloth sandwich wrappers and reusable containers are in.

As kids at Walter Hays Elementary School ate lunch last week, it was clear — at least at this campus — that families have revolutionized their lunch-packing habits in the past few years.

Hardly a Capri Sun or a packet of Goldfish was in sight as hundreds of children nibbled and chattered around picnic tables.

Nearly every student ate from reusable plastic or stainless-steel containers or, in the case of hot lunches, thermoses.

Some had the latest, colorful sandwich wraps and stainless containers available from shops like Live Greene in downtown Palo Alto. But most ate from inexpensive plastic containers made by Ziploc or Glad.

"Instead of bringing apple juice in a juice box, you should bring it in a container," said Joseph, a first-grader.

Across the table, fellow first-grader Caden munched on his sandwich, grapes and an apple from reusable plastic containers, neatly arranged in his lunchbox.

Others ate hot spaghetti, rice or chicken casseroles from thermoses.

Ethan, a fourth-grader, finished eating his sandwich and stashed away a blue cloth sandwich wrapper with a Velcro fastener.

"Hopefully we have a new generation of kids," said a first-grade classroom aide, who asked to be identified only as Carolyn.

"Very rarely do you see a bag of chips now."

Although the day had been designated a special "Zero Waste Lunch Day" at Walter Hays, Carolyn said the minimal amount of trash was much like that of a typical day.

An added benefit of reusable containers is that parents can see what their kids failed to eat when the items come back home in the lunch box that afternoon.

Parent volunteers at Escondido School were surprised to discover more than 20 pounds of completely uneaten food in a single day when they examined lunch trash as part of a "Green Team" project last year.

"Beautiful sandwiches, lovingly made, were completely uneaten — and that doesn't even count the partially eaten items," said Escondido Green Team chair Kristen Anderson.

Plastic water bottles, untouched Odwalla juice drinks at $3 each, whole pieces of fruit and nearly a dozen unopened containers of yogurt were among the items recovered.

"I think parents would rather know about this, so they can ask their child what they would actually prefer to eat. With reusable lunch containers this is much easier," Anderson said.

Most Palo Alto kids are way ahead of their parents when it comes to composting.

Unlike residential households, schools and businesses in Palo Alto enjoy compost pickup from the city's waste hauler, GreenWaste, so kids learn to compost — at least at school — from an early age.

Even the first-graders know that lunch leftovers, including paper napkins and used paper plates, can be put in the school compost bin. And nearly all of the containers from Palo Alto schools' federally mandated hot lunch program, managed by contractor Sodexo America LLC, are compostable.

"It does take time to change behavior, and I think with consistency and positive encouragement a lot can be accomplished," said Walter Hays parent and volunteer Federica Armstrong, an organizer of the school's Green Team.

"Sometimes the kids are really the key in helping the parents learn new habits."

The Walter Hays Green Team plans to sponsor zero-waste lunch days — and track the garbage — on a monthly basis for the rest of the year. Similar efforts at other Palo Alto campuses vary depending on decisions made by each school's Green Team.