Privacy shield is basically a cardboard that is placed around three sides of the student.

Oh thanks.  My son is only in kindergarten but those aren't being used in his class.  Knowing how noisy and busy classrooms can be, I can see how a shield like this might actually be helpful when a student needs to concentrate and get work done and has a hard time doing so when there are lots of distractions happening.  I also understand your concern about your son being "singled out".  Have you talked to him about it?  It could be that he's ok with it (he might even be happy that he's able to be more successful and get his work done).  If he is feeling embarassed I think you should let the teacher know your concerns.  It seems important that your son (and all the other kids) know that the shield is there to help not to serve as a punishment.  If he's being teased for using it, it might be better for him to go to another place in the school (like the library or principal's office) when he needs to concentrate.

Do any other parents have experience with these being used in their kids' classrooms?

I use these in my 3rd grade class for every test.  I think it helps students focus and lets them do their own work.  If a student doesn't have their "partner" sitting next to them that day sometimes they ask to not have one- I'm fine with that. I do have students who ask for them sometimes when the class as a whole isn't using them.  I make them out of plain file folders taped together- I let the students decorate them and keep them in their desks.  In a class with 20 I think it lets them feel like they have their own space to think and feel comfortable.  Ask your son how he feels about it- this isn't something I've ever heard kids comment on.

Hi Mom! I use them when we are testing and everyone uses it. It helps focusing and not copying each other.But sometimes they are used if someone is copying not during a test, and is bothering them. I usually tell the kids if you think someone is copying and it is bothering you, then you can get out our shield( I call them houses.) anytime. But they love them so I do not think it will hurt your child's self esteem. I could also see them used to help students focus too because no one can bother you when they are up. Talk to your son and see what he is feeling. Just talk to him and turn it into something cool! Tell him maybe the teacher thinks the other students are trying to see his answers because he is so smart!!!

I use privacy shields and call them offices.
We use them for tests, but the students also set them up on their own occasionally.  They have been used for just one or a few students with no issues.  There should be no problem if they are introduced to the students as another tool to help them.

You didn't mention what grade your son is in, but I've used privacy shields with fourth graders and first graders with great success. I mainly use them to help my students focus during testing, but they ASK for them frequently! Has your son complained about having to use one?

Oops! Just noticed that you DID identify your son as a second grader.  Sorry that I overlooked that earlier!