1. Give the next piece somewhere to go
A clean stack has a surface you can keep building on and gaps you can still reach. A hole is an empty cell with a block above it. You must clear the covering blocks before filling that hole, so one careless overhang can cost several later placements.
In the teaching board, the four bottom rows are filled except for the rightmost column. That opening is a well. The active I piece is already vertical, but it starts two columns to the left of the well. Move it right twice and check the ghost outline before dropping. The outline shows the landing position; it is a preview, not another solid piece.
2. Compare a safe placement with a quick one
If you hard drop immediately, the I lands on top of the stack. It does not fill the well, so the bottom rows remain. Reset and move right until the ghost reaches the bottom of the open column. A hard drop there fills all four rows and clears them together.
Four-line clears are useful, but waiting for one specific piece while your board grows can be risky. If a single or double keeps the surface playable, take it. The point of a well is a reachable plan, not a rule that every run must wait for an I piece.
3. Make the check before you commit
- Look at the ghost. Does it cover the intended gap?
- Look underneath. Are you covering an empty cell?
- Look at Next. Will your following piece have a sensible landing?
- Leave room near the top. A new piece still needs space to enter.
Hard drop places and locks immediately. Soft drop moves the piece down while leaving you a chance to adjust before it locks. Rotations near walls and floors can use kicks, but a kick cannot rescue every covered hole.
Take it into a fresh run
Open Training and aim for ten clean placements. Do not measure speed yet. After every lock, identify your lowest reachable gap and the next two pieces. If you create a hole, pause and find the placement that covered it. This is more useful than repeating the same fast mistake.