They apply purple so you can see where you’ve put glue, then dry clear—helping you apply glue more accurately and achieve a neat, low-mess finish.
Many school glues are labeled washable and non-toxic; some specify an acid-free formula and are marketed as ideal for classroom use.
Liquid school glue is described as suitable for paper, wood, fabric, and ceramics. Glue sticks commonly list paper as the recommended surface.
Mini hot glue refills are sold in 30-count packs with sticks about 3.94–4 inches long. Descriptions note they are used hot and dry clear for craft and home projects.
Several glue sticks are described as applying purple (or disappearing purple) so you can see coverage while working; they then dry clear.