Bev Lane is an efficiency freak. She is always looking for ways to make her Great Falls home run more smoothly. It drives her children nuts. Lane, a former analyst for the hotel industry, is a stay-at-home mom. She and her husband, John, have three boys and a girl. They range in age from 7 to 14; their daughter is the oldest.

One thing that irritated Lane to no end was the No. 2 pencil waste that was going on in her house and, she suspected, the rest of the world. Those yellow pencils with the little erasers on top had a life expectancy of about two weeks, according to Lane's tracking data, which consisted of watching her children throw the things out once the eraser was gone. After all, what good is a pencil without an eraser?

Sure, she tried to prolong the life of the pencils. She bought those block erasers. "Well, yeah," she said, "kids don't have the foresight to grab the separate eraser, and they are going to sit at the table and ask me to walk the five paces to grab the eraser."

That's not a very efficient use of a mother's time.

She tried those toppers that you can stick on the end of the pencil once the original eraser is worn, broken or chewed off. "Kids quickly realize they are great suction cups," she said of the toppers. "I looked over at my 10-year-old one day and he had four of them stuck to his cheek."

Erasers that can be used as toys don't stay on pencils very long, which makes them most inefficient.

So Lane took it upon herself to solve the No. 2 pencil problem. She invented an alternative. Her new pencil is called a No. 2 Twistil. She entered the design in a nationwide contest held by Staples, the office product company with headquarters in Framingham, Mass.

The Staples Invention Quest drew about 13,700 entries for new office product designs. Lane's idea was chosen as one of the 30 semifinalists. She went up to Framingham last month to make a presentation to a panel of judges, who will select 10 finalists. The winner will be announced next month.

Lane said she enjoyed the trip. "I got to get out of the house without taking a grocery list," she joked.

Her design increased the size of the eraser from a quarter of an inch to an inch and a quarter. She cut the size of the pencil from seven to six inches. The eraser is enclosed in a sleeve that can be peeled away as the eraser wears down.

Lane didn't actually construct a model of the pencil. She submitted a text description of her invention as well as a drawing, which was optional. Lane has a degree in fine arts from the University of Richmond and jumped at the chance to attach a sketch. "You know, I don't do many drawings anymore, so it was really fun," she said.

The pencil is not her first invention. In the name of efficiency, she came up with an organizational chart system for her children a few years ago. "What made it different was that it was an accumulated points system, like a bank account, and they accumulated points over time for doing chores and other things," she said.

The children could redeem their points for rewards. She sold the program to friends and mothers' groups and had a Web site at one point. "But it got to be too much," she said. "The kids didn't like me packing boxes for shipping all the time."

One mother who bought the program suggested that Lane come up with another one for husbands.

The deadline for submitting her invention was June 1, which was a crazy time for her because it was the end of the school year and because a close friend died. She was getting the kids to school events and planning a memorial and fundraiser for her friend as the deadline approached. An inefficient person would have bagged the contest.

Not Lane.

For two or three nights, she sat at the counter and wrote and drew her plan. Her husband would come into the room, look at her and laugh. "He thought I was nuts," she said, laughing.

But she made her deadline and, in a few weeks, she'll find out whether her invention will make its way onto store shelves and help make the rest of the world a little more efficient.