Second layer
Step 3: Move the correct four edges to the second layer.
In the second layer we have 4 centres and 4 edges – no corners.
Obviously none of the edges belonging to the second layer has a yellow sticker. Yellow edges belong to the roof. Now we will use the first time something called an algorithm. Do not be afraid, an algorithm is just a sequence of moves changing the cube in an intended way. We learn and memorize it and then we use it to solve the edges in the second layer.
We look for an edge that has its correct place in the second layer, but is currently on the roof.
In our example, we recognize the blue/orange in position UL. We see further that its wall sticker matches with the L wall (orange). That is exactly the situation we are looking for:
The gap is in the front wall F, either left or right. The target edge we will put into the gap matches with the side wall of the gap (in this case L).
We do the following manoeuvre: L, U, L, U, L, U', L', U', L' (algorithm I)
Our goal in this step
We continue the example (from White Corners)
algo I
Before we look at the result, actually, we analyze this sequence of moves:
We count 9 moves.
The last 4 do exactly reverse the first four moves. If we do not the fifth move at all, the whole cube would remain unchanged.
We memorize it by saying: down, to, down, to, down, away, up, away, up.
Only the wall L and the roof U are turned. The up /down refers to the wall. The “to” means: turn the roof towards the gap, the “away” means: turn the roof away from the gap.
We need a mirrored version, too, where L becomes R' and U becomes U':
Before we go on with the other three edges of the second layer, we will look at our first algorithm executed on a solved cube:
to (U)
down (L)
to (U)
down (L)
down (L)
away (U‘)
away (U‘)
up (L‘)
up (L‘)
You see that the L wall and the roof U become very much scrambled temporarily, but at the end the whole cube is quite ordered again. If we add another U’ move (not necessary for the purpose here), you see that all together just three edges have moved: . The yellow/red, originally at position UL (the one in the L wall next to the gap FL) is now in the gap FL. That was the purpose of this manoeuvre.
Now back to the example. We see the green/red edge matching with the red wall,
but the gap it should go to is in the back wall. We turn the whole cube around and F becomes green again.
We recognize exactly the same situation as before and repeat the manoeuvre:
L, U, L, U, L, U', L', U', L'
The green/orange edge is our next target. We move it by U2 to the matching orange wall
This time we need the mirrored version of the algorithm. The sentence “down, to, down, to, down, away, up, away, up” remains the same. It translates to R', U', R', U', R', U, R, U, R
algo I (right)
The remaining red/blue edge has a blue sticker looking currently to the red wall. We turn the whole cube that blue becomes wall L
By U we move the blue/red edge to the matching blue wall
and do L, U, L, U, L, U', L', U', L' again.
algo I (left)
Second layer completed! (end of this long first example, we use a fresh example for the next step, because by accident we get here a yellow cross and would not need any orientation)
We can encounter the following case: We have yellow edges on the roof only, but the second layer is not yet completed. This means one or more edges are misplaced in the second layer. In our example, the red/green edge is at the correct place but orientated incorrectly. This is easy: With our algorithm L, U, L, U, L, U', L', U', L' we put a yellow edge into that place and the red/green edge is pushed to the roof.
Now we have a situation that we have covered, already. With U we match the green wall sticker with the green wall, turn the whole cube that green is our right wall and execute our algorithm at the right side.
