The middle layer

The bottom layer is finished and it stays finished. White stays down for this step and every step after it — if you find yourself turning the cube over to get a better look, turn it back.

What is left in the middle is four edges: the pieces that sit between two side centres, with no top or bottom colour on them. None of them has yellow. That gives you a way of spotting the ones you need without any thought at all — the pieces you want are the edges in the top layer with no yellow on them.

Matching a piece to its slot

Pick a top-layer edge with no yellow. It has two colours — say green and red — and there is exactly one gap in the middle layer with green on one side of it and red on the other. Your job is to work out which way round it goes in.

Turn the top face until the edge's outward-facing colour sits directly above the centre of the same colour. The face in front of you now shows a vertical bar of one colour: the edge at the top, the centre below it. Keep the cube still from here on.

Now look at the same piece from above. Its other colour is facing the ceiling, and that colour is the instruction. If it matches the centre on your right, the edge belongs in the right-hand slot. If it matches the centre on your left, it belongs in the left-hand slot.

The two algorithms

What the algorithm actually does is a swap. It takes the piece sitting in the slot and sends it up into the top layer, and it takes the edge you lined up and puts it in the slot. That is worth holding on to, because it explains the awkward case further down this page.

1. Find a top-layer edge with no yellow on it.
2. Turn the top face until that edge's front colour lines up with the centre below it.
   U
3. Turn the whole cube, if you need to, so that edge is on the face nearest you. Do not turn the top again after this.
   y
4. If the colour on top of the edge matches the right-hand centre, run the right-hand insert.
   URU^'R^'U^'F^'UF
5. If it matches the left-hand centre, run the left-hand insert instead.
   U^'L^'ULUFU^'F^'
6. Repeat until all four middle edges are in.

When an edge is stuck in the middle layer

Sooner or later you will look at the top layer and find nothing usable — every edge up there has yellow on it. That means the middle edges are already down in the middle layer, but in the wrong slots, or in the right slot with the two colours the wrong way round.

Do not try to correct it in place. Use the swap. Hold the offending slot at the front-right and run the right-hand insert once, with whatever is in the top layer. The stuck edge is pushed up into the top layer, some yellow edge takes its place, and you are back to a position you know how to read.

1. Turn the whole cube so the bad slot is at the front-right.
   y
2. Run the right-hand insert once. Ignore what goes in — you only want the piece out.
   URU^'R^'U^'F^'UF
3. The edge is now in the top layer. Line it up and insert it properly.

What finished looks like

Turn the cube over and the bottom is still solid white. Turn it back and each of the four sides shows two complete rows of its own colour, with only the top row left in a mess. Two-thirds of the cube is done, and everything from here happens in that top layer.