<b>Dear teachers,</b><br/><br/><font color="#0000ff"><b>Monday is the first day of the week.</b></font><br/><br/><font color="#0000ff"><b>Monday is the first day in the week.</b></font><br/><br/><b>Do both sentences sound OK to you?</b><br/><br/><b>LCChang</b>