A/HRC/39/24 discrimination based on gender, sexual orientation and gender identity and expression, and on disability. 55. Mr. de Matteis stressed that prejudices and discrimination had to be approached in a holistic manner in order to show that no form of discrimination was more acceptable than another, thereby also creating a new form of solidarity between all students and pupils regardless of their differences. At the same time, he highlighted the need to look into the details and examine in what way various prejudices and forms of discrimination may have their own characteristics and mechanisms. He noted that teachers could also be the object of prejudice and discrimination, including sexism and homophobia. 56. In the discussion, it was suggested to see children not only as recipients of human rights education but also as participants and stakeholders. Very few children attended sessions of the Human Rights Council or treaty bodies, and thus they did not influence the discourse themselves. However, there had been positive examples of children engaging with the universal periodic review and the Committee on the Rights of the Child, including in pre-sessional lobbying. Furthermore, political change often started at the grass-roots level, which may then trickle up to the national and international levels. Participants also stressed the importance of human rights cities, which explicitly referred to the Universal Declaration of Human Rights and other human rights standards in their municipal policies. F. Contribution of the United Nations to prevention 57. The Chief of the Prevention and Sustaining Peace Section of OHCHR in New York moderated the final session, which focused on the contribution of the United Nations to prevention. The panellists were Pablo de Greiff, Special Rapporteur on the promotion of truth, justice, reparation and guarantees of non-recurrence; Malcolm Evans, Chair of the Subcommittee on Prevention of Torture; and Diego Zorrilla, Resident Coordinator and United Nations Development Programme Resident Representative in Tunisia. 58. Mr. de Greiff referred to his recent reports, in which he had presented an extended argument in favour of a framework approach to prevention.18 He emphasized the important contributions of civil society, which had led, for example, to the abolition of slavery and to desegregation in many parts of the world, and to the expansion of voting rights and successful democratizing transitions. He noted that the work on prevention tended to concentrate on early warning and crisis prevention, and was focused on official State institutions, however he suggested that the prevention agenda should be enlarged to include civil society and interventions in the cultural and individual spheres. 59. In his opinion, the main challenges did not relate to a lack of knowledge but to the low degree of commitment and investment, late interventions and the fragmentation of expertise. Prevention strategies should also include general processes of institutionalization or constitutionalization (at the macro level), effective civilian oversight over security forces (at the meso level) and community policing strategies (at the micro level). He stressed that the United Nations system had a privileged position in articulating a holistic framework of prevention with a broad and upstream approach. He noted that the United Nations had been part of the problem due to its focus on early warning and turf wars between different agencies. He also suggested that the United Nations should improve how it worked with civil society, and should broaden its collaboration beyond non-governmental organizations. The special procedures could also be used more effectively to strengthen the contribution of civil society to prevention work. He recommended fostering networks of civil society organizations, which could facilitate the exchange of knowledge and diminish risks for human rights defenders. 60. Mr. Evans highlighted the experience of practical prevention in the treaty body system through the Subcommittee on Prevention of Torture. Since 2007, the Subcommittee had conducted 65 missions to States parties, visited over 1,000 places of detention and spoken to more than 10,000 detainees. Every State party was also obliged to have a national 18 A/HRC/30/42, A/70/438, A/72/523 and A/HRC/37/65. 13