This case study carried out during the 2020 coronavirus disease of 2019 (COVID-19) lockdown used online data collection means to investigate the distribution of cognitive demand levels of probability and counting principles (PCP) learning tasks in a popular online Grade 12 mathematics textbook, based on the PCP teachers' rating. The teachers' cognitive demand ratings were categorised following Stein's mathematical task framework. Five mathematics teachers from four secondary schools in two provinces in South Africa participated in the study by filling in an online questionnaire. We developed a rating framework named the mean cognitive demand rating (MCDR) to help us interpret the teachers' perception of the tasks in terms of cognitive demand to the learners. Data from the teachers' ratings revealed nearly 65% of the PCP learning tasks in the online textbook were rated as high. Analysis of secondary data from Department of Basic Education diagnostic reports from 2014 to 2020, however, suggests no association between teachers' rating of learning tasks and learner performance. Contribution: This study draws attention to a long-standing underperformance in the topic of probability and suggests classroom-based study that focuses on the learners' rating of the learning tasks themselves to understand clearly how best to support them.