Apple's back to school offer, where you receive a Gift Card, is very clear:
"Qualified Purchasers receive an Apple Gift Card when they purchase an eligible Mac or iPad at a Qualifying Location. Only one Apple Gift Card per eligible Mac or iPad per Qualified Purchaser. Offer subject to availability. While supplies last. Qualified Purchasers shall receive a discount equal to the value of the Apple Gift Card off the price of the eligible Mac or iPad, but will be charged for all items in their cart, including the Apple Gift Card. This offer cannot be combined with the Apple Employee Purchase Plan or business loyalty pricing. Availability of in-store promotion offerings may be limited by Apple Store location closures as a result of COVID-19. Additional restrictions apply"
The full terms of the are outlined here:
Offers - Apple
Prices that you see listed here are already net of the discount for qualifying purchasers - and are not the full retail price that would otherwise be paid.
Where misunderstandings have seemingly occurred are:
a) your possible expectation that the Educational (i.e., already discounted) prices that you see would receive further discount, and
b) misunderstanding of how Apple's offer concerning the Gift Card actually works - as detailed within the offer conditions.
Remember, the pricing that you see is already net of the discount - and that the Gift Card effectively returns to you its face value.