"Start Your Engines: The Chūnin Exam Begins!" (いきなり失格?超難関の第一試験, Ikinari Shikkaku? Chō-nankan no Daiichi Shiken) is episode 24 of the original Naruto anime.
Ibiki Morino appears and announces that the first part of Chūnin Exams is a written test and describes the rules: no asking questions. Ibiki also explains that a team's score will be added up at the end of the exam to see which teams pass. Various chūnin proctors line the sides of the room and watch the genin to catch cheaters. If caught cheating five times, the genin and his/her team are all disqualified. However the test proves exceedingly difficult, and eventually most candidates (Naruto and Sakura are exceptions) figure out the trick to the exam. In order to pass, they have to cheat without getting caught. They then used their respective skills to subtly cheat.
Gaara: Blows sand into another candidates' eyes and uses his Third Eye to read their answers while they're distracted.
Kankurō: Disguises his Karasu as a sentinel and uses it to view other candidates' answers, then goes to the bathroom with the false sentinel to read what the puppet had seen.
Temari: after Kankurō goes to the bathroom, he writes the answers on a small scroll and sublty passes it to her.
Kiba: Uses Akamaru to read the other candidates' answers.
Shino: Uses an insect to read the other candidates' answers.
Tenten: Uses wires to adjust the flaps of a ceiling lamp, to view the reflections of other candidates' answers.
Rock Lee: Tenten uses wires to adjust the flaps of a ceiling lamp, to view the reflections of other candidates' answers and passes them to Lee.
Neji: Uses his Byakugan to see through another candidate's body and read his answers.