I agree with the teacher that it isn’t that uncommon at all.
Some strategies for kids with anxieties
*Don’t remove the trigger. With kids who are worriers, they tend to avoid things that make them worry. But if parents allow their kids to avoid everything that makes them anxious, they may be left with a very limited world—and they won’t learn how to move past their anxieties.
*Help your child build up a tolerance to being away from you. For instance, go to a play date together and sit in another room. The next time, go to the play date and leave for a short period of time. Then leave for longer stretches until your child becomes comfortable even when you’re not there. Try the same tactic at bedtime.
*Instill confidence in your child. Teach your child that this non-dangerous thing—even though it feels scary—is something they can conquer. Let your child know she is strong and capable even without you. And do your best not to let any of your own worries about your child seep into her thoughts.
*Encourage your child to try—and show your support. We want to help our kids be as independent as possible, so you can’t solve this for your child but you can help him get through it. I compare it to climbing a jungle gym: urge your child to try, and if he falls down, tell him he did a great job and help him get back up again.
*Consider a transitional object. They’re not just for little kids. You might make a scrapbook of pictures for your child as she heads off to camp. Or maybe your child will want to wear a piece of your jewelry as a token of how you’re always with her in spirit.
*Make a plan for new situations. If your child is starting a new phase, such as a new school, visit ahead of time and help him imagine what he might expect by talking through his new routine. This can alleviate the fear of uncertainty that may arise when you’re not there. You could even make a little booklet / social story about it.
* Practice positive reframing. Help your child think positively about situations. For instance, if your child is anxious about going to school, remind her that she will get to see her best friend or work on a project she loves—and that she can always ask her teacher for help if needed.

I really like the suggestions from mom160421 – very practical and hopefully helpful.

yeah plus it is getting hotter and the days are longer and stuff.

If you have the time, perhaps you could volunteer to be the teacher’s helper (with the teacher’s approval of course) say once or twice a week for about an hour or so each time. You could help kids with reading, painting etc., and your daughter would absolutely love having you there. She would feel special and it would make being at school more fun. When my daughter started school, although she didn’t really need me there, I volunteered in the school canteen a couple of times a week, and my daughter told me she loved the fact that she could come and see me at recess and lunchtime.

Oh, I thought this question was going to be about when they first started and I was going to recommend perserverence! My son was the same but didn’t take long to get over it. But no, I haven’t experienced this at the end of the year

At this time of the year the littles ones do get very tired and therefore, clingy too. What your teacher is saying rings true, from my experience. It may be worth keeping her home one day, mid week, to help her get some extra rest.