Lifeguards are required to take a CPR certification course once a year. A SCO consists of instructional content on how to administer CPR and questions to assess the learners' knowledge. The learners are able to review the content at anytime to refresh their knowledge. Under a review mode, the SCO is built to only accept their first attempt towards their certification. The SCO is built to only allow the learners to review the material. This would require that the mode be set to or initialized to review, prior to the SCO being launched.
This is only an example of how Mode could be used by a SCO.