How should i tell my mom i lost my ipod touch?

Okay so last week i was helping out at my schools concert then at lunch my ipod touch was in my pocket me thinking it's a bit hefty so i throw it back in my locker or so i think because after school going home i realize hey wheres my ipod and so i thought it was in my locker but next morning i go to my locker and it's not in there anywhere i checked all of it and now i have like 15 different scenarios that i thought of how i could have lost it Did i drop it on the way to lunch? Or did i not close my locker properly after school and someone took it? Either way uh help? it happened last friday and today is wednesday i cant lie and say i only just lost it because i use my ipod as my alarm clock every day and now my mom is like hey i wheres your ipod? I'm like uhh in my bag and now if i say i lost it now she might ask r u sure u lost it THIS week? come to think of it i havnt seen u listening to it what do i do?