(Providence, RI) -- Both sides of the Providence school bus drivers' strike met under federal mediation on Tuesday for the first time since the strike began. The nearly two-week-old strike is being held over a disagreement on retirement benefits, with bus company First Student offering bus drivers the option of participating in a 401-K plan. In a letter sent to First Student on Monday, a Teamsters union representative criticized the company's contributions to 401-K plans for other unions in New England and said First Student has a poor track record with that option. Meanwhile, the ACLU announced yesterday that it has plans to take legal action on behalf of disabled students.