Instead of using the classic alpha system word wall you may also use STEMS that allow for key vocabulary to be displayed under specific categories in a subject.
This resource has STEMS for Math, Science and Social Studies word walls.
You may print on whole page or do multiple on a page depending on your space.
I recommend printing on cardstock and laminating for years of use.
These STEMS are from the mermaid themed collection and can be purchased individually or as part of a bundle (coming soon!)