As promised, here is a post on helping your child learn deep breathing techniques or belly breathing. Deep breathing is a quick trick to help alleviate anxiety and calm worries.
When teaching a child this technique, there are 2 different ways I approach it, depending on the child’s age, developmental level, and comfort. Most children are open about practicing techniques in front of others, but older children may feel a little weirded out when you start asking them to perform belly breathing in front of you, especially if they already have anxiety.
Trick #1-Teaching deep breathing using Bubbles. 
I have a pack of bubbles in my office like this one that I can hand out to children in sessions. I have the child blow bubbles and discuss how hard/soft to blow to get lots of bubbles or big bubbles.
I then suggest this as a trick to help them fight off their worries or (fill in the blank)-tummy ache, jitters, etc.-most of the time children cannot label anxiety/nervousness/worries. But they can tell you what somatic complaints they have easily, which is a sign of anxiety depending when and how often it’s occurring. (Please be advised that tummy aches do not mean your child has anxiety. If you are concerned your child may be experiencing symptoms of anxiety, schedule an appointment for further assessment with a Pediatrician or Mental Health Professional.)
Trick #2- Teaching Deep Breathing using a stuffed animal
Have your child lay down on his/her back comfortably and place a small stuffed animal on their belly.
While directing them to slowly breathe in through their nose and out their mouth, guide them to watch the stuffed animal move up and down on their belly.
This will teach them belly breathing, and they can visibly see if they are breathing correctly. Most times, this is modeled for the child by first doing the technique and then asking them to teach it back to me. Children love to be the teacher! I always end a session reminding them to teach their parent what they learned. This keeps parents involved in progress and helps them hold the child accountable to practice daily.
Alright, that’s it-2 simple ways to help your child practice deep breathing!