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It’s that time of year again: In a flurry of activity, you packed your kids’ lunches, made sure their backpacks were well-stocked, signed all their school forms and started enforcing earlier bedtimes.

If you’re like many parents in the U.S., though, a question might cross your mind as you watch your youngsters saunter off on the first day of school, their new supplies in tow: How did I manage to spend so much money this year?

According to a study by the National Retail Foundation (NRF), the average family with kids in K-12 will spend $669 this season, for a national total of $26.5 billion. That’s 5 percent more than last year.

Here’s how going back to school got so expensive.

Expanding back-to-school lists
According to TeachersLists.com, an online directory of back-to-school lists, this year’s lists are 29 percent longer on average than last year’s. The website also noted that many of the added items, such as plastic bags and tissues, aren’t directly school-related.

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Decreased school funding may help explain this change. A 2014 study by the Center on Budget and Policy Priorities found that 14 states had decreased spending by more than 10 percent per student since 2008. This means that teachers have less to spend on basic classroom items. Instead, those items are added to students’ lists or classroom “wish lists,” driving up the cost of going back to schools.

More advertising
While most companies are spending the same on advertising as last year, some are ramping up their efforts. According to a Nielsen study, 26 percent of retailers surveyed said they planned to spend more on advertising than they did in 2013.

Many major retailers, including JCPenney and Target, started their advertising campaigns in early July, giving families more time to think about what they were going to buy. These factors might have made kids feel more social pressure to purchase the latest and greatest back-to-school items, and that could have made shopping more costly.

Increasing need for electronics
With online research becoming a more important part of many teachers’ curricula, more parents are buying electronic devices for their kids.

According to the NRF, 16.4 percent of parents said that their decisions to purchase electronics were driven by classroom lists; among students going back to college, that percentage is even higher. Because electronics are much more expensive than notebooks and binders, these purchases can multiply back-to-school costs quickly.

Ways to save
Looking for ways to save now that school’s in session? Find out what types of programs your children’s schools already offer. If the school has a computer lab that stays open all afternoon, for example, it may not be necessary to splurge on a laptop.

Some schools also lend students books, calculators, musical instruments, sports equipment and other costly items. Before making another big investment, find out what resources are available.

Encouraging trends
The rising cost of back-to-school shopping can be daunting, but ultimately, it’s a sign of an improving economy. As consumer confidence grows, people feel increasingly comfortable spending more.

NRF President and CEO, Matthew Shay, said he recognized many shoppers want to spend less.

“We expect parents to continue to use caution but also make smart decisions for their family budget that are a good balance between what their children want and what they actually need,” Shay said in a press release.

Before finishing up your back-to-school shopping, look for deals and coupons online and follow your favorite stores’ social media profiles to stay in the loop about promotions. By making smart shopping decisions, you can save a bundle while finding items for your kids that will last.