| Value | Category | 
                                    
                    
                        | 0 | No homework | 
                                    
                    
                        | 1 | Never explains | 
                                    
                    
                        | 2 | Sometimes explains | 
                                    
                    
                        | 3 | Most of time/Always explains | 
                            
            Warning: these figures indicate the number of cases found in the data file. They cannot be interpreted as summary statistics of the population of interest.