Beginner roller skating
There Are Four One-Foot Turns, Not One

Right skate turning right, right skate turning left, left skate turning right, left skate turning left. Four of them, and most skaters only ever practise the one that feels natural. Pick your favourite to build confidence, then drill all four, because the day the pavement decides which way you go, you want to already own that direction. Quad technique, from Najete Kada, a French champion in artistic roller skating.
Ask most skaters to turn on one foot and they will show you a turn. Singular. The one their body picked for them the first week and never revisited.
There are four. Right skate turning right, right skate turning left, left skate turning right, left skate turning left. They are four separate pieces of coordination and being good at one of them tells you very little about the other three.
Pick your favourite first and use it to build confidence, because a move you can already do is what makes the next one feel possible. Then drill all four, deliberately, including the two that feel stupid.
The reason is not completeness for its own sake. Outdoors you do not choose the direction — a car door, a kerb, a bad patch of surface chooses it for you, and you turn the way there is room to turn. Quad technique, from Najete Kada's Tuto roller series. She teaches quad skating and skates it herself; nothing on this page is a claim about inline skates.
Keep going: this is one section of the full Roller Skating for Beginners guide — sizing, gear, stopping, and where to skate, in one page.