The Vashon Island School District has tried begging and even guilt-tripping parents to get their kids to ride the bus during the annual Bus Ridership Week, when the state allocation for bus transportation is determined by the number of students riding during those five days.

Now a group of middle schoolers is trying a different tactic — appealing to parents’ bottom line.

Seven middle schoolers who took part in the Lego League Robotics club this fall decided to find out how many students don’t ride the bus, why they don’t ride it and what the environmental and fiscal impact of their choice is. Each team is expected to do a research project as part of the Lego League competition, along with designing a robot to complete a predesigned ob-stacle course. The project was in line with this year’s theme of solving a local transportation problem.

The group, dubbed Team Ratfish, prepared an online survey, which they asked McMurray teachers to administer to students. About one-third of the school’s students completed the survey, providing a representative sample. Almost one-quarter admitted to never riding the bus, though 95 percent knew that it was “environmentally beneficial to take the bus.”

Team Ratfish then interviewed Tom Dargel, the district’s business manager, to get information about the buses, made some assumptions (for example, the average distance to the school is four miles), found a carbon footprint calculator on the Internet and crunched the numbers. Basing their calculations on 87 students (25 percent of the McMurray student body) not taking the bus each day, they got some eye-opening results.

“Those 87 cars use 12,528 gallons of gas a year, which costs $40,842,” said seventh-grader Sage Levin. “In short, adding two more buses to carry those extra kids would only cost one-10th that amount and use one-10th the amount of fuel.”

So what does that mean to parents’ bottom line?

“It’s costing you $469 per school year in fuel costs to drive your kid,” said seventh-grader Aaron Kitchener. “And by driving, you’re also emitting 2,877 pounds of carbon dioxide. Buses are very efficient in not creating so much of a carbon footprint.”

The total carbon emissions produced by the 87 students turned out to be 245,098 pounds. This compares to 32,345 pounds for two buses.

Team Ratfish members point out that their calculations only take into account students from McMurray who never take the bus (not those who take the bus occasionally), while there are hundreds of students from Chautauqua Elementary School and Vashon High School who also drive.

While Team Ratfish members were mostly concerned about the environmental impact of driving, they realized from the survey results that bus-riding habits may only change by talking about the financial cost to parents. In the survey, students complained about crowded and noisy bus conditions, but the vast majority said they drove primarily because their parents offered them a ride.

“I was surprised that the main factor was parents,” said sixth-grader Alden Rogers. “It’s clear that we need to educate parents about the benefits of buses.”

The school board took away the same message from Team Ratfish’s presentation at the November school board meeting.

“What struck us was that bus awareness needs to be an ongoing thing, not a once-a-year event,” said board member Kathy Jones, whose son, Nick, was on Team Ratfish. “The kids know the benefits. We really need to get to the parents.”

Team Ratfish will be displaying their research at the Science Fair in April, along with the Lego robot that won them second place in the regional competition and helped them advance to the state competition, which was held on Dec. 12. The school board also suggested that the team create a brochure of their research to be shared with parents.

— Lesley Reed is a freelance writer and a parent of a member of Team Ratfish.

Twenty-four students participated in the McMurray Lego League this year, forming three teams. Vashon High School also formed its first Lego League team this year. All competed at the regional level. The program is open to Island students ages 9 and up. Next year’s teams will form in June. To be a participant or mentor in the McMurray robotics program, e-mail VashonRobotics@gmail.com.