One day, every person who walked into preschool said, "It smells so good in here!". Before they even saw the table, they could smell the rosemary.
I don't have much of a green thumb, but a couple of years ago I decided spontaneously to plant a scented herb garden. Lavendar (both varieties), rosemary, spearmint, chocolate mint, sage, Italian parsley, cilantro, lemon thyme, and basil. The hardiest half that survived are still there in the garden!
Last week, we used trimmings from the aroma garden at a sensory table that smelled wonderful.
Be was surprised when I responded to his question "What can we do with these?" with "Whatever you feel like doing!" He immediately got to pouring and grinding and letting me smell his herbal blend.
I won't tell you how to present it to your preschoolers. My suggestion is to just see what they do.
Sea salt (a nice medium for grinding the herbs
and attracts those children who are all about pouring)
Mortar and pestle
A table cover (optional, I used white butcher paper to see the prints after rolling)
add colorful flowers (non-poisonous of course)
add water in small glass jars with droppers and watercolor brushes
add oil in a small squeeze bottle
Add tweezers and magnifiers