The goverinemnt wants to discourage child labour. One policy is considerated. The government is going to reward children who attend school and askes me to assess the impact on child labour market. Specifically, it askes me to explain the process through which the policy affects the equilibrium amount of child labour and wages. Suppse the child labour market is perfect competition and the demand remains constant. Suppose other things being equal.

I think rewards for children would increase the marginal cost of children who choose to work because those children give up the "reward". Therefore, the supply of child labour should be declined and the supply curve would shift leftwards.

Is my anylasis reasonable? thank you. Please only focus on my analysis, there is no need to consider other factors (such as parents, etc)

the most confusing point for me is that whether there is a increase on marginal cost of children who work