Very interesting article about St John's Bread shared by Neil above!

googling "st John's bread recipe" brings up all sorts of interesting things, including this picture and source for the carob/locust pods:  https://nuts.com/cookingbaking...-st-johns-bread.html

This recipe looks yummy but Requires a lot of rising time. But a teacher could bake it for the class. http://fitandfed.net/2016/02/08/st-johns-bread/

Here is a recipe for a quick bread with the carob powder that you could mix in class  it has to bake too long, but the teacher could bake one in advance for the first week's class and the one this week's class makes could be frozen and eaten by the next week's class, etc.  https://hicookery.com/tag/st-johns-bread/

 You can also buy dried carob pods to show the kids and then grind them into a powder and use it as a flavoring or for a taste test.   (You grind the pod itself after you remove the seeds inside them. Those seeds, btw, can be planted!)  Pods are inexpensive and can be purchased online, or check your local Mediterranean or Turkish market. For those who aren't familiar with carob, it is the Middle Eastern equivalent to chocolate.

Happy recipe hunting! If you make or bake with carob, please Share what what you did!