Table 1.

Detailed description of the prevention program

Session	Didactic unit	Description
Session 1	(“Gaming or Gambling”?)	This session began with an icebreaking activity to introduce the program, and make the students feel comfortable with the facilitator. The students were then asked to form teams, and to work in groups. Then, an activity was carried out in order to help students distinguish between gambling and gaming. Each team was presented with images of videogames and gambling activities, and were asked to indicate which of them were gambling. Each team had to compete with each other in order to give the most correct answers. After the presentation of these images, the concept of gambling was introduced, and students were made aware that gambling involves betting money or something of material value on an event with an uncertain outcome, and that humans are unable to control
Session 2	Cognitive distortions and gambling-related misconceptions	This session began with a quiz to recap the main concepts that were covered in the previous session. Then, one student, who was randomly selected in the class, was asked to play roulette, and to show the group the winning number. The other students in the class were asked to form teams, each one comprising four or five members. Secondly, the same student was asked to play roulette again, and to show the group the winning number again. After the second play, each team (based on the outcome of the first two bets) was asked to make their own bets and write their bets on a sheet. Then, the facilitator gave the sheet to the roulette player, who was asked to read aloud the bet of each team, and to again play roulette to see if the number which each team had bet would come up in any of the plays. This activity was followed by a discussion, in which the concept of independent random events was introduced, and it was explained that it was not possible to predict any gambling outcome based on previous plays
Session 3	Attitudes towards gambling and money	This session began with a quiz. The quiz in this session was longer, as this was the first session after the Christmas break, and it aimed to recap the content of the two previous sessions. After the quiz, the students were shown a picture of a young male gambler who went to Las Vegas. After looking at the picture, students were given a short description about the young man. They were told that he was a Portuguese man who used to gamble in his spare time, and that he said that gambling is a very exciting activity. The students were then asked to work in groups again, and to write down on a sheet their opinions, thoughts, and feelings about people who gamble, and if they thought that individuals who gambled had specific characteristics that individuals who did not gamble did not have. After each team wrote their thoughts and opinions, the facilitator collected the sheets, and read loud what each team had written. This activity was followed by a brief discussion, in which the thoughts that students had about gambling were debated. It was noted that there were some stereotypes and labels regarding gamblers, such as being categorized as cool, or having certain traits, but there were gamblers across all ages, and from many social and cultural backgrounds, and it could be a bias to have a stereotype towards people who gamble. After this activity, the students were shown another picture of the same young man, and they were told that he had won 500 euros in one evening in the casino. Then, the students were asked the following questions “Do you think that it is nice to win 500 euros in one evening? Do you think that people who win too much money in a very short period are happier? Do you think that there are other things in life that can make people happy?” After these questions, the students were given a second sheet, in which they were instructed to write about how the day of a happy person. This activity was followed by a final discussion, in which it was concluded that there are important things in life besides money, and that sometimes people who gamble want to win money in a very easy way, but most of the time this will not happen (because it is not possible to predict the gambling outcomes). At the end of the session, students were given a questionnaire about attitudes towards gambling to reflect on their own personal attitudes, and they were told that they were free to share their responses with the rest of the class, if they felt comfortable in doing so
Session 4	Sensation seeking	This session began with a quiz to recap the concepts that were covered in the previous session. After the quiz, the students formed teams, comprising three or four members, and each team had to rank activities that were presented on a PowerPoint slide in terms of the level of sensation seeking that each activity provokes, on a scale from 1 (the activity does not provoke any sensation seeking) to 5 (the activity provokes a high level of sensation seeking and excitement). The activities shown were bungee jumping, taking a trip with no pre-planned routes or timetables, climbing Mount Everest, driving under the influence of alcohol, sleeping in, walking in a dark street where there are no people, going out with people that they have just met, talking on a mobile phone, skipping school, smoking cigarettes, buying a lottery ticket, gambling on bingo, and gambling at an online casino. While each team was ranking each activity, the facilitator wrote the ranks of each team on a sheet, and in the end of this activity, the students were told which activities had the highest score. Then, the students were asked to fill in a sheet for the activities that had the highest score for excitement, adrenaline, and sensation seeking, as well as the three gambling activities. On this sheet, the students had to write down the stimuli, thoughts, feelings, short-term consequences, long-term consequences, and final decision for engaging in this activity. This activity was followed by a dynamic discussion, in which it was explained that there are some activities that cause some high levels of adrenaline, and excitement, but that these feelings were short-lived. In addition, it was discussed that in life when we take a decision if we engage in a specific activity, we need to think about both long-term and short-term consequences. Finally, the facilitator gave the students another sheet, which outlined the steps that people need to take in order to make mature and mindful decisions about engaging in an activity or behaviour
Session 5	Problem gambling	This session began with a quiz in order to briefly recap the concepts that were covered in the previous session. The students were then shown a video of the actor Ben Affleck (known for his gambling addiction) in front of a poker table, and facing another gambling loss. After the video, the students were presented with a newspaper headline which informed them that the gambling behaviours of this actor had affected his marriage with the actress Jennifer Garner. This article added that the couple travelled to Las Vegas, and that Ben bet thousands of dollars, and although Jennifer was very upset with his behaviours, he claims that he could not stop his behaviour. According to this source, Ben mentioned that he felt bad or fed up when trying to cut down his gambling behaviour, and that the actor had been accused of fraud because he had tried card-counting to win playing blackjack. After the video and the newspaper headline, the students were told that the actor was known for his gambling addiction, and then they were asked what aspects mentioned in the video and in the newspaper article that indicated the actor had developed a gambling addiction. This activity was followed by a discussion, in which students were shown in a PowerPoint slide the criteria of problem gambling according to DSM. During this activity, it was explained that for someone being considered a problem gambler, they must show at least four of the criteria. After this, the students were asked to work again in groups, and each group was given a document that showed cases of adolescents with problem gambling behaviour. These cases were taken and adapted from Griffiths (1995). The students were asked to identify the signs and criteria of problem gambling that were present in each of the cases. At the end of this session, the students were given tips about responsible gambling, and were provided contacts concerning relevant institutions that provided support for problem gambling in Portugal