[Trishasales]

I am confused because I was taught in Grade 10 that a NM and NM is covalent and NM and a M is ionic, but this year, in Grade 11, my teacher said that a NM and M bonding together can be covalent. We look at the electronegativity and decide whether the bond or the molecule is polar, non-polar or ionic Whenever I look at the bond polarity of Potasssium Iodide, Copper II Chloride and Sodium Nitrate, it tells me that the bond is polar. But these compounds conduct electricity. Are these compounds ionic or covalent? Which method should I use? Thank you!