D-Cross✓ Completed1 → 1
Front edge: one-move recovery
SituationSee how one F turn displaces the white-green cross edge.
Setup
FExample solutionF'Read the side color before returning the edge.
CASE LIBRARY
D-Cross & F2L cube lessons
Read the state, predict the solution, then verify every move on the 3D cube.
Beginner
Start with one change and a basic trigger.
D-Cross✓ Completed1 → 1
Double turn: still one move
SituationF2 sends the front cross edge to the top with white facing up, yet it counts as a single HTM move.
Setup
F2Example solutionF2The recovery is also one F2 — a double turn is never two moves in this metric.
F2L✓ Completed3 → 3
Right-side pair setup
SituationTrack the corner and edge through the basic R U R' trigger.
Setup
R U R'Example solutionR U' R'Watch the pair rather than the U-face stickers.
Basic
Compare mirrored cases and edge orientation.
D-Cross✓ Completed1 → 1
Right edge: orientation check
SituationA right-face turn removes one D-Cross edge from its slot.
Setup
RExample solutionR'Check both the white sticker and its side-center match.
D-Cross✓ Completed1 → 1
Back edge: read the hidden face
SituationOne B turn moves the white-blue edge where the default camera cannot see it.
Setup
BExample solutionB'Drag to orbit the cube before you answer — never guess a hidden sticker.
D-Cross✓ Completed1 → 1
Rotated cross: whites are not enough
SituationAfter one D turn every white sticker still faces down, yet the cross is unsolved because all four side colors miss their centers.
Setup
DExample solutionD'A solved cross needs matching side centers, not just white facing down.
F2L✓ Completed3 → 3
Left-side pair setup
SituationMirror the basic trigger on the left side while D-Cross stays solved.
Setup
L' U' LExample solutionL' U LCompare the corner and edge path with the right-side case.
F2L✓ Completed3 → 3
Front insert: F' U' F
SituationThe pair edge waits on the far side of the top layer with an orientation that blocks the right-hand insert, so the front face inserts instead.
Setup
F' U FExample solutionF' U' FThe edge's orientation decides whether R or F does the insert.
Intermediate
Practice move order and U2 alignment.
D-Cross✓ Completed2 → 2
Two displaced cross edges
SituationTwo face turns create a short order-of-moves problem.
Setup
F RExample solutionR' F'Restore in reverse order to avoid undoing the first repair.
D-Cross✓ Completed4 → 4
Flipped edge in its slot
SituationAll four cross edges sit in their slots, but the front edge is flipped: green faces down and white faces front. No fix shorter than four moves exists.
Setup
D R D' FExample solutionD R D' FA flipped edge must leave its slot and re-enter from the side — count why one turn can never fix it.
F2L✓ Completed4 → 4
Setup move, then insert
SituationCorner and edge both wait in the top layer, one U apart. The solution U R U' R' aligns them first, then runs the three-move insert.
Setup
R U R' U'Example solutionU R U' R'The first U is a setup move, not part of the trigger — spot the difference.
F2L✓ Completed3 → 3
Pair with a U2 setup
SituationUse a double U turn to change how the right-side pair lines up.
Setup
R U2 R'Example solutionR U2 R'Treat U2 as one HTM move and one playback step.
F2L✓ Completed7 → 7
False pair: split before you insert
SituationCorner and edge sit next to each other on top and look joined, but both are misoriented. The solution splits them with U2 and rebuilds through the front.
Setup
F' U F U2 R U R'Example solutionR U' R' U2 F' U' FA pair is real only when both facing stickers match — check before inserting.
Advanced
Track several pieces through longer sequences.
D-Cross✓ Completed5 → 4
Multi-face cross tracking
SituationFollow all four target edges through five different face turns.
Setup
F R U B L2Example solutionL2 B' R' F'Pause before each move and predict the next target position.
D-Cross✓ Completed6 → 6
Six-move optimal: not the reverse
SituationSix turns bury all four cross edges. The optimal recovery is also six moves, but it is a different path than undoing the scramble backwards.
Setup
R2 F D' L B2 UExample solutionU' L B2 D R2 FCompare the solution with the reversed scramble — optimal is not the same as undo.
F2L✓ Completed7 → 7
Extended right-side trigger
SituationTrack the same pair through a seven-move sequence that preserves D-Cross.
Setup
R U R' U R U2 R'Example solutionR U2 R' U' R U' R'Use the step controls when the pair crosses the upper layer.
F2L✓ Completed7 → 7
Twisted corner in the slot
SituationThe corner already sits in its slot but is twisted, with the edge waiting on top. Two right-hand triggers take it out, pair it, and return it correctly.
Setup
R U R' U' R U R'Example solutionR U' R' U R U' R'Watch the corner's white sticker rotate toward the bottom across the two triggers.
F2L✓ Completed8 → 8
Break a solved corner on purpose
SituationThe corner is already solved in its slot; only the edge is wrong. The eight-move solution lifts the corner out so both pieces can return together.
Setup
F' U' F U R U R' U'Example solutionU R U' R' U' F' U FSometimes the fastest path breaks a solved piece first — follow why it must come out.