To connect these 9 dots with 4 straight lines.
The same line can't be drawn again (no retracing the path).
The extensions:
Can you do it with 3 lines?
Can you do it with 1 line?
Now, its time to back yourself and stop to think, play and investigate before you jump straight to an answer.
This puzzle is an oldie but a gooodie and it really is a challenge in thinking outside the box. That's a clue!
The key to the common solution is to extend most of the lines beyond the frame of dots.
Extension:
For 3 lines it could be that a long line running at a slight angle could be used to zig zag back and forth across the shape while still catching every point.
And, for 1 straight line how about a really fat pen?
Takeaways
Sometimes our patterns of thinking constrain us from seeing the answer.
If you're struggling it can be great to check whether you're introducing an uneccessary limitation.