ANNEX I. >> M  etadata sheets on selected indicators region or area. A break‑up for rural and urban areas is useful in assessing possible disparities across different regions. Comments and limitations  Because of the difficulty of constructing direct measures of the quality of the education being imparted, this indicator is also used as a proxy for assessing education quality, on the assumption that a lower ratio of pupils to teaching staff means better access by pupils to teaching resources. A lower ratio would generally imply that a teacher can potentially pay more attention to individual pupils, which may, in the long run, result in a better performance of pupils. There may be situations where such a conclusion may not be true due to accountability issues and ineffective use of teaching resources. However, a very high ratio of pupils to teaching staff certainly suggests insufficient professional support for learning, particularly for pupils from disadvantaged backgrounds.  “Teaching staff” refers to professional personnel directly involved in teaching pupils. The classification includes classroom teachers; special education teachers; and other teachers who work with pupils as a whole class in a classroom, in small groups in a resource room, or one‑to‑one inside or outside a regular classroom. Teaching staff also include heads of departments whose duties include some amount of teaching, but it does not include non‑professional personnel who support teachers in providing instruction to pupils, such as teachers’ aides and other paraprofessional personnel. The concept of the ratio of pupils to teaching staff is different from that of class size. Although one country may have a lower ratio of pupils to teaching staff than another, this does not necessarily mean that classes are smaller in the first country or that pupils there receive more teaching inputs. The relationship between the ratio of pupils to teaching staff and average class size is influenced by factors like differences between countries in the length of the school year, the annual number of hours for which a pupil attends class, the annual time teachers are expected to spend teaching, the grouping of pupils within classes, and the practices related to team learning. This indicator does not take into account differences in teachers’ qualifications, pedagogical training, experiences and status, teaching materials and variations in classroom conditions, factors which could affect the quality of teaching/learning. Examples of provisions relevant to the right to education and this indicator: Universal Declaration of Human Rights, art. 26; International Covenant on Economic, Social and Cultural Rights, arts. 13 and 14; International Convention on the Elimination of All Forms of Racial Discrimination, art. 5 (e) (v); International Convention on the Protection of the Rights of All Migrant Workers and Members of Their Families, arts. 30 and 43 (1) (a)–(c); Convention on the Rights of the Child, arts. 23, 28 and 29; and Convention on the Elimination of All Forms of Discrimination against Women, arts. 10 and 14 (2) (d). Indicator 12 Homicides (intentional and non-intentional), rate per 100,000 population [e.g., table on the right to life] Definition  This indicator refers to police-recorded cases of intentional and non-intentional homicide per 100,000 population in one year. Intentional homicide is defined as death deliberately inflicted on a person by another person, including infanticide. Non-intentional homicide is defined as death not deliberately inflicted on a person by another person, including manslaughter and causing death by dangerous driving, but excluding non-criminally culpable road traffic deaths. Rationale  Perpetrators of alleged homicides shall be adequately identified, judged and sentenced in accordance with national and international criminal and human rights legal standards. 158 Human Rights Indicators