having artificial fragrances and natural scents from essential oils or seeds [lavender]. We live in a world sprayed full of Fabreeze which has been proven to kill pet birds and clothing that has been doused in fabric softeners after being washed in scented detergents. Even if you THINK your school is fragrance free - it is not, sorry. Unless you have very diligent families who ALL use organic fragrance free household products in all the layers we all use products...it just isn't possible.
I use Meyers Lemon Verbena natural dishwashing soap and it alone makes my room smell wonderful without being toxic. I wash my tables with it using hot water every day. Better that we use bleach, Lysol [which literally makes my skin fall off], scented baby wipes, and alcohol based hand sanetizer until we have no protective pro-biotics left on our skin?
Forgive my rant, but I think a little aromatherapy trial to see how your kids respond is likely going to be okay. I would ask parents for their feedback, noting that you are thinking of introducing some calming natural essential oils in small amounts [and how you plan to use it]. Ask them to sign permission for this trial. Tell them if they have a child with allergies to the lavender and cedar to please let you know and you will not follow through with the trial.
As for lavender and boys, I have had it around my son with no problems for the past 15 years. It may be true or it may be that the boys were drinking too much milk with growth hormones in it...I'm just not sold on the study...
My daughter made a lavender seed/flax seed neck pillow, which when microwaved for a minute warms up and smells wonderful. This weighted warmth would calm anyone.
Again, get permission and you should be just fine.
I know another teacher on PT uses lip glosses that are scented for what she calls "smellies" and puts them on the back of student's hands. She says they last all day. Seems harmless unless you are allergic again. We can't all live in fear all the time, so just ask your families and see if it will work for you.
Hope this helps!