LOS ANGELES — Armed with a list and a shopping basket and resigned to the task at hand, Bill Cook stood in the aisle of a Westchester office supply store perusing shelves of blue, red and black pens, triple- and quadruple-sided pencils, one-hole punches and cap erasers when suddenly a smile creased his face: the chisel-tip markers!

LOS ANGELES — Armed with a list and a shopping basket and resigned to the task at hand, Bill Cook stood in the aisle of a Westchester office supply store perusing shelves of blue, red and black pens, triple- and quadruple-sided pencils, one-hole punches and cap erasers when suddenly a smile creased his face: the chisel-tip markers!

It was a moment of triumphant discovery likely shared by thousands of parents enduring the annual back-to-school ritual of shopping for school supplies. While some families get a head start by purchasing supplies in early or mid summer, many, like the Cooks, wait until the first week of classes for updated lists from new teachers.

All told, back-to-school spending is expected to top $18 billion this year, $3 billion on school supplies such as folders, back-packs and lunch boxes, according to the National Retail Fed-eration. Most families will spend $90 to $100 on supplies — the national average is $94, but the cost can stretch to hundreds of dollars for those with several school-age children.

If the costs of supplies have crept upward each year, the products themselves are likely to seem surprisingly familiar.

Even in this age of Internet downloads, laptop computers and smart boards, there is just no substitute for some simple tools of the trade — a No. 2 pencil and a spiral notebook.

And in some ways, they are more important than ever. As standardized tests and exit exams put more pressure on administrators and teachers to boost student achievement, the importance of having the right materials has never been greater.

"We have ratcheted up the accountability in California in requirements for children beginning even at the kindergarten level, and that demands that children have more school supplies than ever before in history," said Pam Brady, president of the California State PTA. "These are literally tools that children use to learn how to organize — this is your pencil, your pen, this is the folder where you're going to put things. All that organization helps children reach their highest potential."

Although parents may think the lists are a bit arbitrary, they are carefully designed to meet safety and instructional standards, said Bob Huston, principal at Banks Elementary School in Oregon . Parents at each grade level at the K-6 school are provided detailed lists in the spring and can shop on their own or purchase a ready-made kit from the school's parent teacher organization.

"Different types or markers, colors, crayons, scissors, it's all based on what's developmentally appropriate," Huston said. "Just like a carpenter has a chest of tools and different ones are used for different jobs, from grade level to grade level there are differences in supplies that would be needed."

Huston said that if parents ignore the lists, teachers often are forced to pay for them from their own pockets.

"If a teacher sees a child doesn't have something, they are going to go to bat and get something for them, it's just the way they're made," Huston said.

For retailers, the back-to-school shopping rush is equivalent to Christmas as the period of highest sales. The Staples store in Westchester extended its hours and hired extra workers to help with demand, assistant store manager Devin Lee said. As he spoke one recent evening, parents and children with overflowing baskets stood in a snaking check-out line.

Robin Yadach said she and her daughter Gianna, 11, had learned to wait until the first day of school before embarking on their quest.

"Some teachers want binder notebook paper, some want spiral bound and not all the teachers give you everything at once so it involves several trips," said Yadach, as she read from a list suppled by Gianna's art teacher.

Although supply lists are fairly standard, some schools and teachers can be quirky, and for parents, the quest for low odor markers, washable glues and specially ruled handwriting paper can be akin to a scavenger hunt.

All Saints School in Puyallup, Wash., requires earthquake kits for each student, to be stored in the classroom. The outdoor-oriented Colorado Rocky Mountain School in Carbondale, Colo., requires students to bring leather work gloves, water purification tablets and a whistle with neck lanyard, and gaiters — to keep debris out of boots — are highly recommended.

The Los Angeles Unified School District, on the other hand, mostly supplies its own from a 180,000-square-foot Pico Rivera warehouse that stocks 3,000 items, including calculators, chairs, gardening tools, cleaning supplies and special types of construction paper and newsprint that might be hard to find in an office supply store.

Each year, more than 20.9 million paper clips, 11.6 million individual crayons, 4.6 million No. 2 pencils and 1.2 million reams of copy paper are distributed each year, said Dianne Doi, deputy branch director for material management. Still, many schools easily exhaust their supply budget and ask parents to supplement the district's distribution, officials said.

At the other end of the scale, the Catherine Cook School, a private Chicago campus, is using technology to virtually eliminate most supplies for its middle schoolers with school-issued tablet computers that use a keyboard as well as a screen with handwriting recognition capabilities. The students create projects using sound and video, take their laptops home in the evening and submit homework over the Internet.

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Sarah E. Lehman sent her seventh-grade daughter, Eden Schwartz, to the first day of class last week with her laptop, a charger and a single ballpoint pen (just in case), which she has yet to use.

"The kids literally are not bringing any paper to school," said Lehman, who is also director of advancement at the school. "All documents, assignments and worksheets are digitally posted online. These kids are digital natives anyway, and they have completely taken to it."

Although most schools still cannot supply each student with a computer, there is movement to help parents, especially those with limited means, manage costs of school supplies. Several states have annual sales-tax holidays during which school supplies are exempt.

In Tennessee, the Aug. 3-5 sales tax holiday covers school supplies with a purchase price of $100 or less per item. Scissors, sketching and drawing pads, backpacks, glue and paste and binders were exempt. Last year, shoppers in Tennessee saved $15 million on supplies, officials said.

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Still, most families follow the example of Cook, who with 8-year-old son Will in tow, searched for the dry markers, four packets of folders (different colors) and notebooks he would need for his third-grade classes.

As he perused the printed list of glue sticks and markers and other items, he surmised that some were likely back-up supplies for the teacher.

"I know a lot of them spend their own money, so I don't mind helping out," Cook said.

"Oh, Dad," said Will, who was far more excited by the shopping trip than his dad, "did we get a glue that's washable?"