It may not be enough for ministers and local authorities. This week, Jim Wallace, the Liberal Democrat leader, floated the idea of contracts for new recruits that would require a commitment to out-of-hours duties. Similarly, Jack McConnell, the First Minister, wants more in return from a better paid workforce.
Contracts in the independent sector have always stipulated a whole-school commitment in return for a small additional payment, often a few hundred pounds. It appears to work.
Ministers and many others ask why something similar can't be developed when details emerging from the national job-sizing exercise suggest many teachers are actually overpaid for the responsibilities they have.
Differential contracts may not work but teachers will be under pressure to offer more. Or else.