A study in Education Next looks at the impact of double-dose algebra in Chicago Public Schools. In double-dose algebra, pupils are taught algebra for twice as long as normal. From 2003 in Chicago Public Schools, pupils who scored below the national median in their 8th-grade (Year 9) maths exam were given double-dose algebra during 9th grade, with the extra class providing support and extra practice.
An initial study found little short-term effect, but this new study follows the further progress of pupils who are just above the median (who did not receive double-dose algebra) or just below (who did receive the double dose). It found that pupils who had received the double dose had increased rates of high-school graduation and college enrollment. In particular, the intervention was most effective for pupils with relatively high maths skills, but relatively low reading skills. This may be a result of the intervention’s focus on reading and writing skills in the context of learning algebra.
Source: A double dose of algebra (2012), Education Next, 13(1)