Teach your children how to manage a budget during back-to-school shopping.

Fewer than 20 days after the last bell rang for the 2012-2013 school year, big box retailers launched their annual back-to-school promotions.

Advertisements for 25-cent boxes of crayons and brightly colored displays of glue sticks and notebooks dominated the first weeks of July.

In Hampton Roads, the unofficial launch of back-to-school shopping generally takes place during Virginia's sales tax holiday, which begins Friday, Aug. 2.

During the three-day tax holiday, shoppers can purchase most common school supplies free of state and locality retail sales tax.

On July 1, the retail tax in Hampton Roads increased from 5 percent to 6 percent as part of a commonwealth transportation package passed by the General Assembly earlier this year.

To be eligible for the tax exemption, school supplies must cost $20 or less, and clothing items must cost $100 or less.

Eligible school supplies include binders, backpacks, crayons, lunch boxes, notebooks, paint, paper, pencils and textbooks.

It's a time to stock up for many shoppers.

"I start looking at the ads right now, buying and stocking up early," says Kasey Steele, of Newport News. "I have two drawers that I use (for extra supplies) as the year goes by. You can also find great deals on things you might use day-to-day or you can use for gift-giving throughout the year. Crayons put with some coloring books go so good for birthday presents when you aren't trying to spend an arm-and-a-leg."

What it will cost

Shoppers will be more frugal with their back-to-school purchases this year, according to a survey by the National Retail Federation.

According to the report, families with school-age children will spend an average $634.78 on apparel, shoes, supplies and electronics, down from $688.62 last year — about an 8 percent decrease.

Clothing and electronics will make up the bulk of that $634 figure, with 55 percent of parents spending about $200 on electronics. This year, there is a heavy emphasis on tablets and smart phones in anticipation of the new school year.

To match retailers' urge to get shoppers in stores early, more parents are hitting the stores now.

"We continue to see a shift in shopping patterns during big spending 'events,' where consumers typically head out early to take advantage of fresh inventory options and initial markdowns, then see a lull only to rev back up again when final sales appear," Pam Goodfellow, consumer insights director for the retail federation, said in a written statement.

As for college students, they also will spend less this year. But at an average $836.83 that's a hefty August bill.

"Millennials are extremely different from previous generations when it comes to personal style and décor," Goodfellow said.

Retailers like Bed Bath & Beyond have promoted special advertising sections geared toward college students. The focus: Luxurious bedding and essentials that also serve a decorative purpose.

There's a technology element, too. Even desk lamps serve the dual purpose of charging mobile and tablet devices.

Shopping the tax holiday