If you are looking to make something similar, I suggest you check out the Water Bottle Flowers instructions on the Crafts by Amanda blog which are pretty similar to the ones that the kids made at Gia's preschool.
All you need to make them is some clean & empty plastic water bottles, stickers for the base (the flower pot), small photo of your child, a clean straw with bendable neck, paints or markers to color the flower petals, fish aquarium gravel (or small pebbles), scissors & glue. A great rainy day or school project for sure!
Head on over to Amanda's blog and check out her instructions which are pretty similar to how these kids made them. In addition, you can find a ton of upcycle & recycle craft projects on Pinterest or by doing a Google search.