Whoever wrote that isn't clear about how the system works. MOE pays by qualification. There is no difference in pay scale of Primary & Secondary school teachers.

In Singapore, teachers are quite highly paid. According to salary benchmarking website payscale.com, secondary school teachers receive annual salaries of $70,782, or about $5,900 a month. Primary school teachers earn just a little bit less: $68,314 a year, or about $5,700 a month.