since that's my profession but you may also use many of the strategies as an adult if needed. This is a copied email sent to a parent with an elementary aged daughter with anxiety issues.

Some of the things that can help at school are to give her a couple break cards she can use if needing to leave the classroom for a couple minutes to collect herself. These can be reassuring just knowing it's available and would include her going to get a drink, walk a lap around the halls or use the restroom. This should only be a few minutes but she can use one of the coping/calming strategies on the menu card while out. The best strategies are those that help the child "get through" rather than "avoid" situations they're uncomfortable with. I'd also suggest you go over the strategies on the coping skills menu so Estella can learn when and how to use them as needed. These things can often be a stage that need not last too long if handled with compassion but as a teaching opportunity for learning valuable skills.
I've provided some links to some resources you might find helpful as a parent. One very important key is to understand that children will look to the adults they trust for how to handle challenges. If we take them in stride and show confidence in their resiliency, they will become resilient themselves. Let me know if you have any questions or if there's anything else we can do. His/her teachers will also be happy to do what they can to help.

http://www.adaa.org/living-with-anxiety/children

http://www.heysigmund.com/anxiety-in-kids/

http://www.childmind.org/en/posts/articles/2015-4-13-anxiety-classroom

http://www.anxietybc.com/parent/anxiety.php

http://www.pbisworld.com/tier-1/

This one has links to classroom interventions that can also be tried at home where appropriate or discussed with the teacher for implementation there.

http://childmind.org/article/how-anxiety-leads-to-disruptive-behavior/?utm_medium=email&utm_source=childmind&utm_content=7+-+How+Anxiety+Leads+to+Disruptive+Behavior&utm_campaign=weekly+091916&source=weekly+091916

http://childmind.org/article/why-childhood-anxiety-often-goes-undetected-and-the-consequences/

http://childmind.org/article/what-to-do-and-not-do-when-children-are-anxious/?utm_medium=email&utm_source=childmind&utm_content=9+-+What+to+Do+and+Not+Do+When+Children+Are+&utm_campaign=weekly+091916&source=weekly+091916