I asked a similar question before but no one answered.<br/><br/>Which is ok?<br/><br/>These children were <u>fifth- to sixth-grade</u> students.<br/><br/>THese children were <u>fifth-to-sixth grad</u>e students.<br/><br/>This reflects <u>a medium to high level</u> of knowledge.<br/><br/>This reflects <u>a medium-to-high level</u> of knowledge.<br/><br/>This reflects <u>a medium to a high level</u> of knowledge<br/><br/>Confused. Please help.