Eliminate obvious choices in the mobile app
"Tap the Pairs" exercises have an even number of tiles so the final pair is an easy match. I often reflexively tap them without much thought. If there were an odd number of tiles, the last match would require some thought and improve learning. "Tap the Pairs" exercises should be like the sentence exercises which have leftover tiles.
Good idea! (And a lingot for you. Although you probably have enough with a 1000+ day streak.)
Agreed. Also, the "3 choice" one is also too easy, the other two answers never even remotely make sense.