Which of the following is not true about the "Children on board" sign on school buses?

The statement that it is only used when the bus is in operation is not true because the "Children on board" sign is relevant not only when the bus is actively in operation but also when it is stationary. The purpose of this sign is to alert other drivers to the potential presence of children in the vicinity of the bus, fostering a heightened awareness of safety concerns regardless of whether the bus is moving or stationary. The sign is crucial for ensuring that drivers remain vigilant, especially in areas where children are boarding or alighting from the bus, which can happen even when the bus is not in motion. Therefore, maintaining awareness of such a sign is important for enhancing overall safety in school zones.