Intervention group students will receive a series of five tobacco-related comics during the 2-week study period.

Control group students will receive five conventional health leaflets or related educational materials.

A series of five comics are developed specifically for this study. The comics will address five key themes which we found could be reinforced based on our previous project. This includes [1] the harms of tobacco use, [2] secondhand smoke (SHS), [3] thirdhand smoke (THS), [4] alternative smoking products (ASPs), and [5] the tobacco industry and tobacco-related policies in Hong Kong and worldwide.

Students reported their opinions towards 5 statements in both pre-test and post-test:

1) Smoking accelerates skin ageing; 2) Secondhand smoke can trigger asthma and middle ear infections in children; 3) Opening windows or using a fan can eliminate the effects of thirdhand smoke; 4) E-cigarettes with added flavors are harmless to the body; 5) Hong Kong prohibits smoking while queuing for public transport.

Questions may be subject to change, as they will be adjusted according to the leaflets/comics, while maintaining a similar format.

Students' knowledge will be assessed using a 3-point Likert scale, with each item rated on a 3-point Likert scale ranging from -1 (wrong) to 1 (correct).

Students will report their opinions towards 5 statements: 1) Banning smoking in all places would harm smokers' rights; 2) I will actively avoid secondhand smoke; 3) Using e-cigarettes is safer than smoking traditional cigarettes; 4) Tobacco companies use various methods to encourage people to smoke; 5) The government should ban the sale of flavored smoking products.

Questions may be subject to change, as they will be adjusted according to the leaflets/comics, while maintaining a similar format.

Students' attitudes will be assessed using a 5-point Likert scale, with each item rated on a 5-point Likert scale ranging from 1 (Strongly disagree) to 5 (Strongly agree). Item scores will be recoded as appropriate, so that higher scores consistently reflect more negative attitudes.

Students were asked: If one of your good friends offers you a traditional cigarette, e-cigarette or heated tobacco product, ask you to have a few puffs, and no one will know about this as no more smoking in the future. Will you use them?

Students' intention will be assessed using a 5-point Likert scale, with each item rated on a 5-point Likert scale ranging from 1 (Definitely no) to 5 (Definitely yes). Lower scores indicate a lower intention to use ASPs.

Students were asked: In the past 7 days, how many days (0-7) 1) was someone smoking next to you when you were at home? 2) do you smell secondhand smoke drifting in from outside when you were at home? 3) was someone smoking next to you when you were outside home? 4) you can smell cigarette smoke on objects or people when you are at home and no one is smoking, and you don't see any smoke?

Each item was rated on an 8-point scale ranging from 0 (0 days) to 7 (7 days), with higher scores indicating more frequent exposure to secondhand smoke (i.e., a worse outcome).