randomly generated replacement list from the original frame. Forty percent of the original sample was replaced.<sup>12</sup> The study sample was randomly divided into a control group (176 students) and three treatment groups (consisting of 107 students each). Treatment group 1 (T1) received a digital library of freely available (non-curriculum) fiction/non-fiction reading material. Treatment group 2 (T2) received the digital library _and_ core curriculum textbooks in Mathematics and English. Treatment group 3 (T3) received the digital library, the core curriculum textbooks _and_ supplementary instructional material. Supplementary materials included open source materials curated by curriculum experts to provide both remedial and current instructional content. To benchmark the impact of eReaders on school participation against a non-technology, a random subsample of 70 students from the treatment groups– identified via a cross design orthogonal to the treatment and stratified by treatment group – were read a short script by a trained enumerator on the expected returns to education in Lagos.<sup>13</sup> The experimental design is presented in Figure 1.

A baseline school survey covering 214 schools in Lagos was conducted in November 2010 before the intervention began with a series of workshops in August 2011. During these workshops, students completed a self-administered, 45-minute survey and test to capture data on student characteristics and reading comprehension and ability. The test included publicly released test items used in the Grade 5 English–Language Arts Standards Test (one of the California Standards Tests administered as part of the Standardized Testing and Reporting (STAR) Program).

After the survey and test, students in the treatment groups were provided eReaders and given a short orientation on the device. For control students, a placebo session was organized wherein students participated in a short talk about the potential of technology use in education. Students in t <mark>he cross-designed information treatment group received the returns to schooling information at the close of the workshop.</mark> <mark>Endline student testing was conducted during workshops in April 2012, just before students sat the JS2 end of year exam All students completed a self-administered survey and were given 45minute tests on</mark> reading comprehension and ability (as was done at baseline), math, and non-verbal intelligence.

<mark>The Math test included publicly released items from various years of the Trends in International Mathematics and Science study (TIMMS) Grade 4 test.</mark> The timed non-verbal intelligence test was based on Raven’s Progressive Matrices, which assesses general intelligence or “general cognitive ability” by measuring the ability to form perceptual relations and to reason by analogy (Raven 2003).

Students were asked to bring their eReaders to the endline workshops, and information on device use and status was collected through the self-administered student survey, direct observation of the device, and extraction of use information from the device.

> 12 Nearly half of this “attrition” is due to class repetition. See Table 1.1.

> 13 Using information from a set of sampled workers from an investment climate survey, we generate information on the returns to schooling for completion of primary, junior secondary, senior secondary school and tertiary schooling.

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