The law prohibits any sex-based discrimination, which means both treating women better than men as well as the more common treating men better than women. Therefore, all things being equal, the employer should treat a single mother better than a married man.However, that said, if all circumstances aren't equal--if, for example, owing to child care needs, she can only work on particular shift, while he has more flexibility--an employer may be able to take that into account; in that instance, it is making a decision based on specific circumstances and employee availability, not gender. This is similar to how an employer could choose to accomodate an employee who is also a student by scheduling around classes. Therefore, while in a general sense, the employer may not do what you ask, in specific situations, it will come down to the facts and whether the accomodation is based on employee need, not gender.