apprenticeship traditions. But the apprenticeship only starts at the later stages of secondary education. The program has 45 percent private funding from companies. In addition, it is not only flexible but also selective and prestigious. It is not unheard of that one starts out in an apprenticeship program but becomes a professor later (Atkins 2017).

Figure 2.10 Percentage of vocational program enrollment in total upper secondary enrollment <!-- Start of picture text --> 90.0%<br>80.0%<br>70.0%<br>60.0%<br>50.0%<br>40.0%<br>30.0%<br>20.0%<br>10.0%<br>0.0%<br>2005 data 2015 data<br>Czech Republic Austria Slovak Republic United Kingdom Belgium Netherlands Switzerland Finland Luxembourg Australia Italy Norway Germany France Sweden OECD average Denmark Poland Spain Turkey Iceland Ireland Portugal Korea Hungary Mexico United States China<br><!-- End of picture text --> _Source:_ OECD 2007, 2017.

Even in countries where tracking starts relatively early, students tend to follow the same common core curriculum for a large share of their upper secondary education. In Germany, students follow entirely similar curricula for the first two years so that the selection of specific branch of study can be deferred. In the Netherlands, students follow a common core curriculum, usually for the first two to three years of the secondary education in different streams. The common core curriculum specifies the minimum skills that should be acquired by all students, although the level of study may vary depending on the type of school concerned. The three types of lower secondary school in Liechtenstein also offer the same basic common curriculum but in the Realschule or Gymnasium, the curriculum includes additional elements.

In the United States where upper secondary education focuses on general skills, there is evidence that students can benefit from having meaningful career readiness and vocational-oriented courses. Arkansas provided a compelling case study of integrating “Career and Technical Education” (CTE) in general upper secondary study. Beginning with the class of 2014, all high school students must take six units of “career focus” coursework to graduate, which they can fulfill with CTE. A followup assessment found that the more CTE courses students take, the better their education and labor market outcome, especially for students who take at least three courses of the same discipline to form a “concentration,” who are 21 percentage points more likely to graduate from high school than otherwise identical students (Dougherty 2016).

For most countries, the theoretical debates over student tracking are generally around the trade-off between efficiency and equity. Proponents of tracking argue that it is economically efficient to group students by ability to create more homogeneous schools. Educators could tailor curriculum and their pedagogical approaches for the given set of students. In particular, not all students may benefit from an upper secondary education with substantial academic content. Opponents of tracking argue that since tracking is largely based on academic ability, it condemns students placed into the lower tracks to lower educational attainment, as young people in vocational training are less likely to invest any more in education and training than those in more general tracks, leaving 18