In 1996, HISD instituted a national norm-referenced achievement testing program in an effort to continue its commitment to academic achievement. During the 1997-98 school year, the Stanford Achievement Test Series, Ninth edition (Stanford 9) was administered, for the first time, in the fall. During the 1998-99 school year, the first spring administration was completed.

The Stanford 9 assesses student achievement in reading, mathematics, language, environment/science, social science, spelling, study skills, thinking skills, and listening.

The district policy is that all students, except students with certain Special Education classifications, in grades 1-11 who receive reading and language arts instruction in English are required to take the Stanford. Students with limited English proficiency (LEP) in grades 1-9 who receive reading and language arts instruction in Spanish are administered the Aprenda in place of the Stanford.

From 1999 to 2001, Harcourt Publishing utilized Spring 1995 norms in the calculation of normal curve equivalents (NCEs) and national percentile ranks (NPRs) for HISD students. Beginning in 2002, the Spring 2000 norms were employed. Harcourt has determined that the 2000 norms are slightly more rigorous than the 1995 norms.

Aprenda: La Prueba De Logros En Español Segunda Edición (Student Achievement): The Aprenda is a norm-referenced achievement test that measures HISD Spanish-speaking students’ academic performance when compared to the performance of Spanish-speaking students from a nationally representative sample. The test contains subtests in reading, language, mathematics, thinking skills, and English. All subtests, except calculos matematicos (mathematics computations), are developed in Spanish. The calculos matematicos subtest was directly taken from the Stanford Achievement Test Series. The Aprenda is used by the district as the Spanish-language companion test  to the Stanford testing program.

The Aprenda 2  was administered beginning in September 1997 to all LEP students in grades 1-9 who receive reading and language arts instruction in Spanish.  Administration of the Aprenda 2 using the 1996 norms continued through 2002 when the Aprenda (first edition) was administered using the updated 2001 norms.