The two sources disagree on the effectiveness and feasibility of recycling programs in schools. Source 1 emphasizes the necessity of school districts' participation for recycling to significantly impact the environment, indicating that successful programs require the involvement of many people. In contrast, Source 2 mentions the challenges of getting all students to follow a recycling program, suggesting that such programs may be ineffective despite their importance.
Thus, the correct answer is: Successful recycling programs require the participation of many people.