What's the difference in use between lagar mat and lagar?
I just completed a lesson that used 'lagar mat' several times.
Jag lagar mat -> I cook
The last question asked me to translate 'cook'. The multiple choice answer was 'lagar'.
Is the 'mat' not always required? What's the difference is usage?
It's literally the same expression as the English "to fix food," as in, "Would you like me to fix you something to eat?"
Att laga by itself is to fix something, like laga fönsterglas, 'to fix window glass.'
You could say laga just to mean cook, it's super common in my experience (as long as you're using laga in reference to something), and you can think about it in the same sense that you can say fix to mean cook in English, as in Jag ska laga dig nåt att äta, 'I'll fix you something to eat.' Other cooking-related words include koka (in the sense of boiling/simmering) or steka (in the sense of frying/grilling), although koka is also used to mean brew, as in att koka te, 'to brew tea.' (As opposed to brewing coffee, which would be att brygga kaffe.)