Children always want to ask question after question; parents shouldn't get annoyed.
Tips
memory
The pun is on 璺 (a crack in pottery) and 问 (to ask), both pronounced wèn. When a sand pot (砂锅) cracks, the crack runs all the way to the bottom. The image: keep cracking/questioning until the fracture reaches the very bottom.
history
Recorded in the modern educator Tao Xingzhi's 《普及现代生活教育之路》. The variant 打破沙锅问到底 (with 沙 instead of 砂) is equally common and has the same meaning.
