I'm looking for a child-friendly word to say that a certain object is [neither big nor small].
It's for dialogues of the kind:
A: My pencil case is big.
B: My pencil case is ?????.
C: My pencil case is small.
This was for a 6-year-old. She didn't know the word to use and I suggested 'average size', but someone suggested 'average' was a difficult word for a 6 year old. Not being a native speaker, I didn't insist. The exchange not being particularly friendly, I refrained from asking for a word the person might deem more appropriate for children.
I am, however, thinking about using that kind of dialogue with my classes of children and, again, I was hoping for something that sounds simple.