Sampling was done in two stages. First, schools were sampled, then classrooms within schools. The exact procedures used varied by country, but in each case procedures were adopted that were expected to yield a sample representative of the instruction received by eighth-grade mathematics students in each nation.

Teachers and students who appeared in the main study tapes were guaranteed confidentiality: videotapes of their classrooms can only be studied by researchers who have applied for and received a license from NCES. In addition, five "public use" tapes were collected in each country as examples to help communicate the results of the study. Teachers and students who appear in these tapes were not part of the main study, but agreed to be filmed and to have their lessons made available for public viewing.

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