Using WorldEdit in Minecraft EDU:
Download the appropriate version. This is by SIsilicone.
Enable the resource & behavior packs.
In your world, type /tag @p add worldedit.
Navigation Wand will tp you or let you sneak through walls: :navwand
Grab a wooden axe and type :wand to make a selection wand. Mark the first corner while sneaking and the second corner without sneaking. Your selection should be highlighted. You can also use :pos1 and :pos2 to mark the corners as the position you are currently standing in (not on).