The WhatsApp application has taken the education system by storm: class groups of students with and without teachers, teams of teachers forming collaborative groups, and groups of principles sharing information and professional advice with each other. A new and popular phenomenon has been added to all of this in recent years: WhatsApp groups shared by teachers (mainly homeroom teachers) with students' parents. The studies that have investigated the function of instant messaging applications (mobile instant messaging [MIM]) in the educational context have mainly focused on the educational potential of these platforms. Moreover, most of them dealt with more mature learning environments such as colleges and universities, while neglecting the field studies on the functioning of the school-age social network. This study aims to explore the relationship between teachers and parents in Israel through WhatsApp: the main content that emerges in this interaction, the motives, and goals that parents and teachers have in using this channel, and the challenges and limitations of using WhatsApp given its unique affordances: the public nature of the channel, the extreme availability, and the interactive configuration that mimics a face-to-face conversation. These issues provide an up-to-date look at the characteristics of the relationship between teachers and parents in the digital space and the ways in which popular communication technologies shape and influence this space.

The Role of Affordances in Group Dynamics:
Availability and Over-Availability
As mentioned earlier, the teachers and parents reported an active use of the WhatsApp group and positively mentioned the technical features that make this possible, such as accessibility ("Every parent in the class has WhatsApp [...] it saves me a lot of phone calls": Galit, sixth-grade teacher), simplicity ("Emails are much more complicated you have to attach files... here it's much easier [...] I just send a picture or a video to the group and it gets them in the mood": Anat, second-grade teacher) and immediacy ("You get information immediately and there are 30 people who can potentially respond...": Tali, mother of a fourth-grade girl). As one of the mothers concluded, "It's like having the teacher in the palm of your hand" (Sarit, mother of a third-grade child).

At the same time, a large portion of the parents found the intensity of the discussions in the group oppressive and overwhelming: "There can be several messages in a few minutes and then it really gets out of hand" (Gadi, father of a third-grade child); "I put the group on silent. Everyone replying to anything that comes up [...] it becomes a competition to see who has decorated the text message with more flowers, hearts, and balloons, which is nice but also annoying" (Tamar, mother of a third-grade girl).

The teachers mentioned another important aspect of the groups' activity: the parental expectation of total availability. According to one teacher, "Parents sometimes overdo it because they feel they have to get attention and an immediate response to every message" (Galit, sixth-grade teacher). As a result, some teachers stated that they consciously limit themselves to partial availability. Anat, a second-grade teacher, said, "When it suits me, I answer, and when it doesn't suit me, I don't answer. Sometimes I'm available and I answer, and when it's not convenient for me, I don't answer. I'm not the parents' secretary!".

Keywords: Teachers and parents communication, WhatsApp, social networks.