I need to alert parents about an urgent situation, should I send a smart alert or an urgent alert? 

Smart Alerts: Smart alerts are a great way to make your parents and staff aware of less critical situations such as early dismissal, school testing, and school activity cancellations. They have flexible recipient options so they can be sent to specific groups and classes within the school. Smart alerts give you the option of sending the content via text, voice, email or all three. Smart Alerts can be auto-translated and sent to parents via their home language preferences. 

Urgent Alerts: Urgent alerts should be used to send out information that requires parents' immediate attention like threat alerts and natural disasters. Urgent alerts can only be sent out to either the entire school or district. With urgent alerts, you can select a pre-recorded message from the library or write a short message that gets sent out through all communication modes: email, text and voice call (as text-to-speech). Urgent Alerts can be auto-translated and sent to parents via their home language preferences, or you can turn this off and enter your own translations. Here is a help article that details the differences between smart alerts and urgent alerts.