Whether the band teacher's sample is biased depends on various factors, including how the question is asked and who is being asked.
If the band teacher only asks students in his first bell class whether they like playing musical instruments, then the sample could be biased if this class does not represent the entire student population at the school. For example, if the first bell class consists mainly of students who are already enrolled in the band or have a particular interest in music, then the sample would be biased towards students who are more likely to like playing musical instruments.
To obtain an unbiased sample, the band teacher would need to survey a random or representative sample of students from across the entire school, ensuring that all types of students are included in the survey. This would provide a more accurate picture of the overall student population's preferences towards playing musical instruments.
