For safety, I would recommend sending out essential agreements to the students and parents before hand. Maybe have the agreements signed and returned to you before the call. The agreements ensure that participants are respectful during the call and are aware of things that make a successful call such as muting the microphone when not speaking and taking turns, among others. I would encourage making sure that parents (or caregivers) are involved in getting the students connected.
Below is a tutorial showing how to set up a call and send a link to the call for parents and students to connect. The link can be sent via e-mail as opposed to the class blog, for security reasons.