The Beautiful Boy Modelling School hired Keith to prepare commercial artwork for its company materials. Upon completion of the work, Keith invoiced the school for $1600 and was promptly paid. Later, when he realized that the modelling school was using the artwork more extensively than he was originally led to believe, Keith sued the school and its president, Dan, for copyright infringement. Dan, who was not only beautiful but also a lawyer, argued that Keith's allegation of copyright infringement fails because his contract did not contain any limitations on the use of the work by the modelling school. Moreover, Dan argued that common business practices establish that in the case of work for hire, the commercial artist assigns all copyrights to the employer unless explicit restrictions are included as part of the terms of employment. What factors can the courts consider in determining whether the school has infringed Keith's copyright? How could Dan, as a prudent business manager, have avoided this situation?