F2L: pairs, not layers

Eight trips or four

Your cross is done. In the layer-by-layer method, the next step was four white corners, then four middle-layer edges. That's eight separate trips, and on every one of them the finished part came apart for a moment, only to be put back together.

Speedcubers put a corner in together with the edge that shares its column. The duo is called a pair, and the whole stage is called F2L, short for First Two Layers. Four pairs, and two layers are done.

It sounds like expert-level stuff, but you can start F2L without memorizing a thing. You do it intuitively, by understanding where each piece is headed. Six short tricks and turns of the top are all you need. That's what this chapter and the next two are about: they're the bridge from layer by layer to CFOP.

A pair and its slot

Take one pair: the white-green-orange corner and the green-orange edge. At home they form a column at the front right, the corner on the bottom and the edge just above it in the middle layer. That spot is called a slot. There are four slots, one for each pair, and the centers tell you which is which: this one has green and orange on its sides and white below.

A pair is solved when its corner and edge sit in their slot the right way around: white facing down, and the side stickers matching the neighboring centers.

The golden rule of intuitive F2L: work only in the front-right slot. To bring the slot you need into that spot, turn the whole cube around its vertical axis, keeping yellow on top and white on the bottom. This turn is written y, and the cube spins the same way the top layer does on U.

Open, turn, close

All of intuitive F2L is built on three moves in a row. R raises the front-right column: the slot is open. U moves whatever came up out of the way. R' brings the right face back down: the slot is closed. The pair has ridden up to the top, at the front left, and pieces from the top layer have taken its place.

Keep an eye on the white cross edge on the right. R lifts it into the middle layer, U leaves it alone, and R' puts it back. Its other neighbors move only for a moment, too. When the dust settles, only the top layer and one slot have changed, so the cross and any finished pairs come through untouched.

There are just six tricks: three with the right face, R U R', R U' R' and R U2 R', and three mirror images with the front face, F' U' F, F' U F and F' U2 F. Together with turns of the top, they solve any pair whose corner and edge are on top or in their own slot. A computer checked all 150 such positions and found no exceptions.

A ready pair: four moves

Here the corner and edge are already joined: they sit side by side, and their colors match on both faces they share, green on top and orange on the right. That makes them a pair, a single block. The corner's white sticker faces you.

To insert it, play U R U' R'. U moves the pair to the left, away from the slot. R opens the slot. U' swings the pair precisely into the raised column's place. R' lowers it home.

If the pair lies along the front face with white facing right, mirror everything: U′ F′ U F.

Try it yourself: the mirror-image insert

The pair lies along the front face, white facing right. Insert it with the mirror-image trick you just saw. This time the front face does the work: F′ raises its right side and opens the slot. If you get stuck, start with U', which moves the pair away from the slot.

The easy case: three moves

Sometimes it's even simpler. The corner sits directly above the slot, white facing right, and the edge is on the far side of the top, green facing up. Watch the first move. R raises the right face, and the corner rides to the back, where it lands snug against the edge. The pair has joined itself! U swings it over to the open slot, and R' drops it in. Three moves: R U R'.

In the mirror-image easy case, the corner sits above the slot with white facing you, and the edge is on the left side of the top. Then the answer is F′ U′ F.

Remember these two pictures: the ready pair and the easy case. Everything from here on boils down to them.

Try it yourself: turn the top first

This is the easy case, except the corner isn't above the slot. Turn the top until it is, with white facing right; the edge will land on the far side. Then play the three familiar moves.

A pair, or just neighbors?

Before you insert anything, make sure the corner and edge are really joined. There's just one rule: they sit side by side, and their colors match on both faces they share. Here the corner and edge are neighbors, but on top the corner shows orange and the edge shows green. That's not a pair. Insert it, and you'll build the wrong column into the slot.

Common mistakes:

• Turning D or L. The bottom is your cross, and the left side holds other pairs' slots. Intuitive F2L needs only U, R, F and whole-cube turns, y.
• Inserting mere neighbors. Check both shared faces first.
• Reaching for a far slot. If the slot you need is at the back, don't contort your wrists. Turn the cube.

So how do you join a corner and an edge that are both on top but not yet a pair, like these two? That's the next chapter.