Maybe i'm just a little slow but I think an indication around which elements can be interacted with would aid a lot in teaching the players the mechanics. Also having it start automatically forces the player to find the answer much faster, almost turning it into an action game of sorts. Maybe having it be continuous, and success being triggered when multiple enter in a row? Like, three in a row = win, so the ones that are dying can let you experiment without having to reset and waiting for them all to travel again.
I love the themeing of having the scaling blocks be terminals