Lesson 3 of 4
Threats
4 min

The 7 Trap in Connect Four: Two Threats in One Column

The first trap every player learns is two threats in two columns. The 7 hides both threats in one column, one right on top of the other, and blocking the lower one gives away the upper one.

Step 1 of 5

Two threats, one on top of the other
Red's discs make the shape of a 7: a bar of three across row 4, and a stroke that runs down and to the left from the bar's right end to row 2 of column 1. Each line of three has one open hole, and both holes are in column 4, on row 4 for the bar and row 5 for the stroke.

Column 4 holds two discs, so the next disc there lands on row 3. If Yellow drops it, Red wins on row 4. If Red drops it, Yellow has to block row 4, and Red wins on row 5.
Build the 7
Here the 7 is missing its corner. Two Red lines point at the same empty hole: the bar on row 4, and the diagonal that starts on row 2 of column 1. One disc in that hole finishes both.
Your move
Drop the disc that makes two threats in column 4.
Can Yellow defend?
Back to the finished 7, with Yellow to move and no Yellow threats on the board. What can Yellow do about column 4?
Question
Spring the trap
Yellow played somewhere else, on row 2 of column 7. Don't wait for Yellow to drop into column 4: drop there yourself. Here a disc under your own threat is the right move, because both threats are yours.
Your move
Drop into the hole under your two threats, then connect four.
Stop the 7
Now you play Yellow. Red's 7 is one disc from done: a Red disc in the corner hole, on row 4 of column 3, would finish it. Once it is built, nothing in column 4 helps.
Your move
You are Yellow. Stop Red from building the 7.

What you learned

Two of your threats in one column, one on top of the other, win that column: blocking the lower one hands over the upper one, unless your opponent can make the lower hole a threat of their own.
The 7 is a three across and a three on a diagonal whose holes sit one on top of the other.
To spring it, drop under your own two threats. The block on the lower one gives you the upper one.
Stop a 7 before it is built: take the hole where its two lines meet.