In this step, you are going to learn how to solve the second layer of the 3x3 Rubik's Cube. This might get a little bit hard and tricky.
Triggers is the common algorithm of solving the second layer. Just like in Step 2. There are 2 version of triggers shown below.
Basic Algorithm: Right Trigger - R U R', Left Trigger - L' U' L
What this algorithm does is take out the corner piece and putting it back.
Solve the Second Layer. In other words, putting all the edges on its solved position.
YOUR GOAL
Begin by finding an edge piece without a yellow sticker on it.
Look on the side of the edge piece.
Match the edge piece to its center piece.
Look above the edge piece (This is just like Step 2 pieces).
If the edge piece is matching the right side of the center color, perform a U + right trigger.
If the edge piece is matching the left side of the center color, perform a U' + left trigger
Look on side of the corner piece you just took it
Match the corner piece diagonal to its center color.
If the corner piece matches the center piece diagonal on the right side, perform the right trigger without a U
If the corner piece match the center piece diagonal on the left side, perform the left trigger without a U'
Special Case: If you have solved all the edges and you looked around and you have one edge flipped, then you have the special case.
If an edge piece is on the left side, perform a left trigger
If an edge piece is on the right side, perform a right trigger