F2L, intuitively

This is the lesson that matters. Learning the last layer properly saves you perhaps five seconds; learning to see F2L saves thirty, and it is the difference between reciting a method and solving a cube.

The slot

Once the cross is done, the bottom two layers need eight more pieces: four corners and four middle edges. They pair off. The corner that belongs between the front and right centres, and the edge that belongs directly above it, live in the same gap. That gap is a slot, and there are four of them.

F2L means filling a slot with both its pieces in one go. Instead of eight separate jobs you have four, and each one is about eight turns rather than sixteen.

Open the slot, then close it

Hold the cube with a slot at the front-right. One turn of the right face lifts whatever is in that slot up into the top layer and leaves the slot open. One turn back puts it down again.

That is the entire mechanism. Every F2L insertion is: open the slot, arrange the two pieces above the hole with a turn of the top, and close it. R U R' is the whole method in three turns.

The two insertions

Everything below assumes the slot is at the front-right, with white on the bottom. Call the two colours of that slot the front colour and the right colour; the corner carries both of them plus white, and the edge carries both of them and no white.

1. White facing right. The corner sits in the top layer above its slot with white on the right-hand face. Put the edge at the back of the top layer, showing the front colour upwards. Now: the first turn opens the slot and takes the corner out of the way, the second brings the corner and the edge round together so they meet, and the third closes the slot on both of them.
   RUR^'
2. White facing you. Same corner position, but white on the front face. Now the edge belongs on the left of the top layer, showing the right colour upwards, and the whole thing happens on the front face instead: open, bring them round, close.
   F^'U^'F

Those two sequences, mirrored round the four slots, solve a good half of all F2L cases outright. Notice that neither of them was memorised — each is the same three ideas in a different order, and you can rebuild either one at the cube if it goes out of your head.

When the pair is already joined

Sometimes the corner and the edge are already side by side in the top layer, showing the same colour upwards — a two-piece block. You cannot open the slot underneath them without breaking them apart, so move the block out of the way first, open the slot, and bring it back.

1. Corner above the slot with white facing you, edge immediately to its right, both showing the front colour on top.
   URU^'R^'
2. Corner above the slot with white facing right, edge immediately in front of it, both showing the right colour on top.
   U^'F^'UF

When white is on top

Here is the case that defeats people. The corner is in the top layer with white facing upwards. There is no way to join a pair around it, because the white sticker has to end up pointing down and it is currently pointing at the ceiling.

The fix is to use the slot as a place to turn the corner round. Put the corner into the slot the wrong way, which leaves white on the side, and then take it out again.

1. Hold the corner above its slot with white facing up, and its edge in the top layer beside it on the right.
2. The first three turns tuck the edge out of harm in the neighbouring slot, carry the corner across the top and bring the edge back. The corner now has white on the side, which is what you needed.
   RU²R^'
3. And now it is the first insertion you learnt, from the top of this lesson.
   U^'RUR^'

When a piece is already in the slot

A slot with the wrong things in it is not a special case. Take them out with the same turns that put things in, and then solve it normally. The habit to break is nudging: a piece that is nearly right is still wrong, and lifting it out is nearly always faster than working round it.

1. Corner in the slot but twisted, edge in the top layer. The first three turns lift the corner out and turn it so white faces the side; the last four are the insertion you already know.
   RUR^'U^'RUR^'
2. Corner already correct in the slot, edge still in the top layer. Take the corner back out, set the edge against it, and put both in from the front. This is the beginner middle-edge algorithm, and now you know why it looks the way it does.
   URU^'R^'U^'F^'UF
3. Both pieces in the slot and both wrong. Lift the pair straight out into the top layer, then treat it as any other case.
   RU^'R^'

The other three slots

Everything above was written for the front-right slot. The quickest way to use it everywhere is to turn the whole cube — a y rotation brings the next slot to the front-right — and solve every pair in the same place with the same fingers.

That is a fine way to start and it is what most people do for the first few months. In time you will learn the back-right slot in place, using the left hand, because a rotation costs about as much as two turns. Do not rush it: a rotation you can do without thinking beats an in-place solution you have to work out.

How many turns a pair should take

Three turns for the luckiest cases, seven or eight for most, eleven for the worst — that is the range. Four pairs comes to about thirty-two turns, and with the cross the first two layers should be around forty.

If a pair is taking you twenty turns, the answer is almost never a missing algorithm. It is one of three things: white was facing up when you tried to pair, you broke a finished slot and had to repair it, or you inserted into the slot next door. Slow down and look before the first turn.

Practising it

• Solve the cross and the first two layers only, then scramble again. The last layer teaches you nothing here.
• Do it slowly enough that you never stop moving. Speed is the last thing to add, not the first.
• After each pair, ask which two pieces you will do next, before you start turning.
• Count the turns for a single pair now and then. Anything past twelve is worth replaying.