A rota system would ensure smaller class sizes making social distancing achievable, and reducing strain on public transport in the mornings and afternoons, says the National Education Union.
Buses still support millions of essential daily trips, and for many people provide the only practical, frequently used method of transport other than walking.
Provisions in the Trade Bill let ministers change laws like the Equality Act without parliamentary scrutiny, in order to implement international trade agreements.
The Local Government Association has warned that nearly half of all bus routes in England currently receive partial or complete subsidies from councils and are under threat.