Is selling "Sawa" scratch cards to female teachers in installments, with the cards being received and then returned to the seller for him to sell them to the distributor from whom he bought them, considered Islamically prohibited?

There is no harm in selling "Sawa" cards by installments at a price higher than the cash price. It is permissible for the female teacher to authorize the seller to sell the card, provided she takes possession of it first, and does not sell it to the same distributor from whom the seller purchased it, because this is considered a usurious ruse called "the tripartite ruse." However, selling it to another party other than the distributor is permissible, though it is preferable for the female teacher to sell it herself or authorize someone other than the original seller.