2.4. Randomization
In consideration of the practical feasibility of the experiment, the intervention method must be kept consistent in each class to avoid pollution, so we carried out random grouping by class number. A randomization master list was compiled from computer-generated random numbers, and each class was assigned to a group (experimental group, control group) by the biostatistician, using opaque envelopes to hide the assignment results.To ensure comparability of baseline information between the two groups, the baseline data of the two groups were statistically analyzed after grouping, and it was found that there was no significant difference between the two groups.