Good evening everyone,

I'm a first year teacher so unfortunately my content knowledge is still developing. Today we were working with momentum and I had a student comment "We are always working with kilograms and we say that it's the SI unit for mass, but I see it used all the time with weight. Why is it used for weight and mass if it's the official unit for mass?"

After contemplating an answer for her all day to not exceed an 8th grade level I unfortunately have no idea how to properly answer her question. I don't want to say anything wrong to confuse her. Can someone please help me develop an answer for her? I want to give her the information tomorrow if I can and me already not knowing makes me feel incompetent.