Mnemonic: Something used to help you remember.
Qalqala is best described as an “echo noise” or “bouncing noise”. There are five qalqala letters. If any of them appears with a sukoon on top, you perform qalqala. (Prime example, if you have no idea what qalqala is: the end of the last word of every verse in Surah Ikhlass.)
Qalqala letters: qaff (ق), ba (ب), taw (ط), jeem (ج), and dal (د).
The mnemonic to remember them is “qutb jadd” (قطب جَدّ). Qutb means “pole”, jadd means “grandfather”. Grandfather pole…
Some letters are easy to do qalqala on — even qaris (reciters) make mistakes on them! Learn them and avoid them. (To stop yourself from doing a qalala on a letter, simply stop on the letter.)
Common qalala mistakes: ‘ayn (ع), daad (ض), ta (ت), and kaf (ك)