The Hibiscus is a member of the Mallow family.
You know you have a member of the Mallow family when you find a funnel shaped flower with 5 separate petals and a distinctive column of stamens surrounding the pistil. There are also 3-5 partially united sepals. If you crush any part of the plant from this family and rub it between your fingers and you will notice a slimy substance or texture, called mucilaginous in botany terms. Okra, for example, is in this family. Harrington Harmonies has a wonderful notebooking page for Mallows that you might want to use.
It is this family that the treat we know as Marshmallows come from. Confectioners in early 19th century France made the innovation of whipping up the marshmallow sap and sweetening it, to make a confection similar to modern marshmallow. The confection was made locally, however, by the owners of small sweet shops. They would extract the sap from the mallow plant's root, and whip it themselves. The candy was very popular, but its manufacture was labour-intensive. In the late 19th century, French manufacturers thought of using egg whites or gelatin, combined with modified corn starch, to create the chewy base.
For fun, you might want to make a batch of homemade marshmallows. Since this recipe uses gelatin and cornstarch, it really has nothing to do with the plant family, except that your students might associate the plant family and the confection if they make them while you are studying this family.
Put 3 envelopes of unflavored gelatin and a 1/2 cup of water in your mixer's bowl and let "bloom" for 10 minutes. Meanwhile add 2 cups of sugar, 2/3 cup of white corn syrup and 1/4 cup water in a saucepan. Bring to a boil and boil 1 minute. Turn on mixer and drizzle boiling syrup into the mixer's bowl. Turn mixer up and add 1/4 teaspoon salt. Turn mixer on the highest setting you can without losing the contents of the bowl. When it fluffs around the sides, stop the mixer and scrape down the sides of the bowl. Turn back on high and continue mixing until the volume stops increasing. (This whole process should take from 8-12 minutes.)
Add 1 Tablespoon of vanilla extract and mix in. Add coloring now, if you wish. Pour into baking dish and smooth with a spatula. Coat a 9 x 13 inch baking dish with butter and powdered sugar. Cool overnight.
In the morning, invert the baking dish over a cutting board coated with powdered sugar.
Cut into squares of the desired size.
Dredge squares in powdered sugar until not sticky. Keep in an airtight container until ready to use.