As parents check off items on their children's back-to-school supply lists, there's something else they often need to buy.

A backpack.

While kids may think they know what they want, teachers know what they need. So we asked Westlake teachers for their insights on what parents should look for when buying a backpack.

How big?

Lisa Forshey, a teacher at Holly Lane Elementary School, said elementary school students need a backpack big enough to hold a full-sized folder and one three-ring binder.

Deb Schrembeck, a seventh-grade language arts teacher at Lee Burneson Middle School, said lockers need to be taken into consideration.

"(Backpacks) need to be able to collapse to about eight inches wide to fit," she said.

Burneson students should have a backback big enough to hold five three-ring binders, Schrembeck said.

Forshey said having a backpack big enough to hold a lunchbox was helpful for younger students.

"If they can put (their lunchbox) in their backpack, it lessens the likelihood of their losing it," she said.

Schrembeck reminded Burneson parents that the course books for core subjects math and language arts are also online and that parents will have the access code for them. That means students do not have to carry those books, which weigh about five pounds apiece, home, she said.

Schrembeck also recommended getting a sports-style backpack with side compartments for things like phones and iPods (both of which are allowed on buses), and pens and pencils.

Features to Skip

Neither teacher was a fan of rolling backpacks.

"A few students have them," Schrembeck said. "But the halls are so congested, they're hard to use."

Forshey agreed.

"With the younger students, it's a safety issue in the hallways," she said. "Also, wheels make the backpacks heavier."

Skip themed backpacks, Forshey advised. 

"Go simple and save yourself the trouble," she said. "Kids' tastes can change fast."

Your daughter may now be all "OMG I LOVE JUSTIN BIEBER!" and want a Justin Bieber-themed backpack, Forshey said, but all it will take is one snarky comment from a Mean Girl, and she'll be begging you to replace it.

Check the straps, Schrembeck said. Make sure they're adjustable and nicely padded so they sit comfortably on your child's shoulders.