Keep the yellow cross while exchanging its misplaced edge pieces.
By the end: distinguish adjacent from opposite matching edges and finish their positions.
With yellow up and the lower two layers solved, turn U until at least two yellow edges have side stickers matching their centers. If all four match, this checkpoint is already complete. Inspect every side, not just the two in the solid view.
If the two matches are adjacent, regrip the entire cube around its vertical axis until the matching sides are back and right. Do not use U to move an already matched pair into that viewing position; U moves edges relative to the centers and can destroy the matches.
At the previous checkpoint, each of the four upper edges has yellow facing up. An edge can satisfy that direction test while occupying another yellow edge's home. Its second sticker tells you which home it needs. With green front on the teaching cube, the yellow-green edge belongs at upper-front, the yellow-red edge at upper-right, the yellow-blue edge at upper-back, and the yellow-orange edge at upper-left. Use the centers on your own cube for these relationships. This side arrangement is a model, not a verified description of your puzzle.
A match means that the side sticker of an upper edge has the same color as the center immediately below it. Do not compare it with a nearby corner sticker, which may be unsolved, or with the lower edge's current color as a substitute for reading the center. On the front face, inspect the middle square of the top row and the center square. Repeat around all sides. A yellow cross gives no information about these comparisons, because yellow can face upward while the side colors are rearranged.
To align is to turn the upper layer relative to the centers. A U turn changes which edge lies above each center, without disturbing the solved lower two layers. Try at most the four distinct upper alignments before deciding the case. These are the present position and the positions after one, two, and three U turns. A fourth U returns to the first. Stop searching as soon as all four match, or when a useful pair appears. This inspects a finite set, not an instruction to spin U indefinitely.
Why is a pair available? Across all four upper alignments, each edge matches exactly once. There are four individual matches in total. An offset counts U quarter turns needed to reach home. If each alignment had one match, each edge would need a different offset. Four different offsets total six quarter turns. This cannot balance the ring, because moving four pieces among four slots requires total offsets divisible by four. Thus some alignment has at least two matches. You need not calculate offsets while solving.
To use that fact, first record the colors. Read the side edge colors in front, right, back, left order, then compare them with the same four centers. After U, repeat those comparisons. Two matches identify pieces to protect during setup. With four matches you are already finished. Exactly three matches cannot occur when the four correct yellow edges fill the four top slots, because the remaining edge must occupy the remaining home. Recheck the fourth comparison before trying an algorithm for an apparent three-match case.
Classify a two-match result by the positions of the matches. Front and right are adjacent, as are right and back, back and left, or left and front. Front and back are opposite; right and left are opposite. The top diagram shows adjacency, but its yellow squares do not reveal matches. Read the side stickers first and then mark those positions mentally. When the back or left side is hidden, use the net or inspect the physical side. Guessing the unseen match would undermine the setup that protects it.
Use R U R' U R U2 R' U. Its last U is part of the sequence. This exchanges the front and left top edges while leaving the back and right top edges in place. It also changes corners, which we have not finished yet.
If your two matching edges are opposite, use this sequence once from any front orientation. Then turn U to find two matches again. You can now arrange an adjacent matching pair at back and right and use the sequence again. Inspect after each complete sequence rather than repeating indefinitely.
The exchange sequence has eight written moves, R U R' U R U2 R' U. The U2 is a half turn, so it moves the upper layer twice as far as a single U, though it occupies one written token. Keep the grip fixed. Its completed effect on upper edges is specific. Front and left exchange their pieces, while back and right return to their original edge positions and directions. Corners also move. Do not assume this means the rest of the upper layer stays unchanged.
Use Adjacent matches as a worked example with green front and red right. The initial side edge colors in front, right, back, left order are orange, red, blue, green. Thus right and back match their centers, while front needs the green edge currently at left. The orange edge currently at front belongs left. One front-left exchange repairs exactly those two errors. This is why you hold the correct pair back-right. You are choosing a grip where the algorithm's moving pair is precisely the pair that needs exchanging.
Track the yellow-green edge rather than a stationary square. In this example it starts at upper-left with yellow up and green facing left. After R U R', it is at upper-back with yellow still up and green facing back. After the next U, it reaches upper-right with yellow up and green facing right. The following R takes it out of the upper layer temporarily. Its stickers stay attached throughout this route. The remaining moves return it to the top and send it to upper-front, where green matches the green center.
The view immediately before the final U is especially instructive. All four upper edge stickers already face up, and the lower layers have returned. However, the side edge colors in front, right, back, left order are orange, green, red, blue. None matches the corresponding center in this example. The last U changes that order to green, red, blue, orange. Now all four match. Stopping early would make a correct algorithm look unsuccessful. It could encourage a repeat when only the required final alignment turn was missing.
At intermediate moves the upper yellow cross itself may disappear. After the first R in this example, the upper-right edge square shows green, not yellow. That temporary disruption does not contradict preserving the cross at the complete sequence boundary. Likewise the lower layers are not protected after every individual face turn. The meaningful comparison is the state before all eight moves against the state after all eight. Earlier insertion lessons used this boundary discipline too, but here the boundary includes the final U and the U2.
There are related beginner variants with different final alignment instructions. Do not combine their stopping point with this lesson's written variant. Learn this exact ending, U2 R' U, and compare the side colors only after finishing it. If an attempt leaves the cross up but side colors wrong, reconstruct the last moves before choosing another algorithm. Undo last turn reverses a known simulator mistake. If you cannot reconstruct a physical error, reidentify the earliest unfinished checkpoint instead of assuming that repeating the exchange will repair every kind of mistake.
The yellow cross can remain visually perfect throughout this stage while its side colors change. That is why looking only at U cannot tell you whether the edges are solved.
Check four side-center matches and the preserved lower layers before moving to corners. Keep the final U in memory as part of this exact variant; other tutorials sometimes use a variant with a separate alignment turn.
Suppose an adjacent matching pair is currently at the front and right. Your aim is to call those same two matched relationships back and right, without changing either relationship. Rotate the whole cube around its vertical axis while keeping yellow up. A y' regrip brings old left to front, so old front becomes right and old right becomes back. The matched pieces move together with their centers. They remain matched, even though their positional names have changed. The new front color need not be green.
Contrast that regrip with a U turn. U moves only the upper edges and corners, leaving the side centers where they were. An edge that was above its matching center now sits above a different center. A top turn can help find an alignment initially, but it cannot merely rename an already matched pair. Thus the first instruction says align U and the second says regrip. Both actions involve movement around the vertical direction, yet they change different relationships. Watch centers and edges to check which action you performed.
After regripping, say the new front and right center colors before beginning R. Face letters name positions in your grip, not permanent colors. On the drawings, a sticker letter R means the color red; an instruction R means turn the right face. Similarly a blue sticker carries B while position B means back. If the front center is orange after your setup, the first R still means your current right layer. Keeping this distinction prevents a correct regrip from being followed by moves aimed at the old grip.
The opposite case needs a different first purpose. In the Opposite matches preset, the side edge order starts green, orange, blue, red with green front. Front and back match, while right and left are exchanged. A vertical regrip cannot turn opposite positions into adjacent ones, because rotating the whole cube preserves which sides oppose each other. Apply the exchange once from this grip to change the arrangement, rather than trying to force the opposite pair into the adjacent setup. The first exchange prepares an adjacent case, not the final correction.
After that first exchange, the preset's side edge order is red, orange, blue, green. Only back matches in this alignment. A dropped match count does not invalidate the method. Turn U to inspect new alignments. A U' from this state gives green, red, orange, blue, so front and right now match. Regrip y' to put those matching sides at right and back. The new center order is orange, green, red, blue; the side edge order is blue, green, red, orange. Front and left are now the two wrong edges.
| Complete action | Side edges F, R, B, L | Centers F, R, B, L | Matches |
|---|---|---|---|
| Opposite preset start | G O B R | G R B O | Front, back |
| One full exchange | R O B G | G R B O | Back |
| Then U' | G R O B | G R B O | Front, right |
| Then y' | B G R O | O G R B | Back, right |
| Second full exchange | O G R B | O G R B | All four |
One more complete exchange fixes exactly that prepared front-left pair. This worked route uses a U' and a y' for brevity; the demonstration can show three U turns and three y turns with the same net effects. Both routes reach the same setup; neither is a universal shortest solution. After any opposite-case exchange, inspect rather than assuming the preset's exact colors. The dependable rule is to find matches again, recognize an adjacent pair, and regrip so that pair occupies the positions the exchange leaves unchanged.
R U R' U R U2 R' U
Begin a practice attempt by selecting Adjacent matches in the independent cube below, not merely in the demonstration above it. Read all four side comparisons before pressing a move button. The prepared pair should be back and right, so no setup is needed for this start. Close the recall cue and attempt the complete sequence. Wait for turns to finish before comparing completed solid and net states. Check my progress does not solve or align anything. It reports whether this practice cube has reached the required checkpoint.
Stop after the seventh written move, R', and inspect without asking Check to correct the state. The cross should be back, yet the side matches will still be wrong in this preset. Predict what the final U will do, then perform it and inspect again. This separates recognizing a yellow cross from recognizing solved yellow edges. It also tests the exact variant's ending. Restart this attempt before trying from memory again, because a success that relied on the visible demonstration's move list did not test unaided sequence recall.
To test setup recognition, restart Adjacent matches and use the regrip that brings the original right face to front. The matching sides now appear at front and right. Before executing an exchange, choose the regrip that returns them to back and right. Read the centers to confirm the change. For a wrong-setup contrast, compare what a single U does to those same relationships, then undo it. Undo reverses the actual practice history one turn at a time, not an abstract stage or the cube in your hands.
Next select Opposite matches and state why no regrip alone can give the adjacent setup. Execute one exchange and inspect the new side colors. Use the U buttons to find the new alignment, then the regrip buttons to put the adjacent pair back-right. These separate control actions let you check which decision caused an error. If you open Show a recall cue, close it and restart a prepared attempt afterward. The evidence is whether you can choose and complete this route unaided, not how often you viewed it.
When checking the finish on a physical cube, inspect the upper middle side sticker on every face, including back and left. Also confirm that all four yellow edge stickers still face up and that the two lower layers remain solved. Yellow corners can still be misplaced or twisted, so a partly yellow upper face is not a reason to repeat the edge exchange. Conversely, four matching side stickers do not excuse a missing yellow cross or a damaged white layer. Checkpoints include prerequisites; later progress must not conceal earlier errors.
| Observation | What it establishes | Next action |
|---|---|---|
| Cross up, four side matches, lower layers solved | Yellow edges are complete | Stop exchanging; inspect corner homes next |
| Cross up, wrong side matches | Orientation alone is complete | Inspect alignment and pair setup |
| Correct finish after opening the cue | Helped completion in this attempt | Close cue and try a fresh preset attempt |
| Known missed last U | Incomplete exact variant | Finish that U before deciding a new case |
Stop this stage as soon as the cross, four side-center matches, and lower layers are correct. The next task judges corners by all three colors before trying to twist them. Do not use the edge exchange to fix corners simply because it moves them. For recall, state the entry check, the alignment search, the adjacent regrip, the opposite-case detour, and the exact final U in your own words before a fresh attempt. A correct simulator state verifies that attempt's sticker relationships. It does not establish permanent memory, dexterity, or a speedcubing result.
Prepared states isolate one task. Some examples happen to finish the whole cube; on a general scramble, stop at the stated checkpoint and continue with the next unfinished step.
Hold the matching edge side stickers at back and right. Exchange front and left.
Next: R. right face: clockwise quarter turn, viewed directly from outside that face. Completed 0 of 8 moves.
RUR'URU2R'U
Sticker letters are colors: W white, Y yellow, G green, B blue, R red, O orange. Face names are positions: U top, D bottom, F front, B back, R right, L left. Read B and R in context.
The net shows the last completed turn; the solid view shows the turn in progress. Presets replace the starting state and reset playback. Reset keeps the selected example. Do not copy an autoplay demonstration onto your cube unless your starting state and grip match. Use manual steps for following along.
Start from a prepared state. These controls change this practice cube only. They do not control the demonstration above or your physical cube. Goal: Match all four yellow edges to their side centers.
0 moves in this attempt. Limit 500; undo or restart if reached.
R U R' U R U2 R' U
A cue is help, not a failure. After using it, restart the prepared state and attempt the same task without reopening it.
Sticker letters are colors: W white, Y yellow, G green, B blue, R red, O orange. Face names are positions: U top, D bottom, F front, B back, R right, L left. Read B and R in context.
Face turns and whole-cube regrips animate in the solid view; the net updates when the turn finishes. Reduced motion shows the result immediately. Wait for a turn to finish before starting another. Undo can cancel the current turn. A new preset or Restart cancels motion, replaces the entire attempt and clears its history. Undo reverses only the last practice turn. Check does not move pieces or reveal an automatic solution. State is local to this page and is not saved after reload.
Your two correct edge side stickers are at front and right. Should you turn U to put them at back and right?
You want to change the viewing labels without changing edge-center relationships.
No. Regrip the whole cube around its vertical axis until the matched sides are back and right. A top turn moves the edges away from their matching centers. Then perform the exchange sequence.
The whole yellow cross faces up, but the front and left side stickers are exchanged. Is the yellow-cross algorithm the right correction?
The edges are oriented; their locations are wrong.
No. Keep the matching back and right edges in place and use this lesson’s front-left exchange. The yellow-cross algorithm solves a different problem and can undo edge orientation.
The explanations, simulator, and diagrams are original. These references support standard notation and beginner procedures. The course keeps white down, including the final twisting stage. Do not mix its final sequence with a tutorial that flips the cube over.
These examples use states produced by legal turns. The simulator has no sticker-painting input and does not diagnose physically twisted, reassembled, or damaged cubes. Successful model checks do not establish physical-device usability or long-term recall.