What she (and you) see as her explaining is what the teachers see as back chat.
Example:
Your DD arrives at a lesson. She has lost her pencil case. She sits down, realises she does not have anything to write with, and asks her mate who sits across the classroom if she can borrow a pen.
What the teacher sees:
The teacher has put a starter in the board for the students to get on with for the first five minutes while she does the register.
-your DD is not doing the work (because she doesn't have a pen)
- your DD is calling across the classroom and disrupting others doing their work
The teacher then tells your DD off (on two counts).
Your DD is upset and responds with something like "I was just trying to borrow a pen you can't give me a consequence for borrowing a pan".
Teacher then tells off DD for backchat.
How to fix:
Give her one of the disposable pencil cases I linked to before
Ask the Senco to arrange with her teachers that each teacher has one of those disposable pencil cases for her
Teach your DD to put her hand up and ask the teacher if she can borrow a pen from a friend as she is sorry but she has forgotten hers
Ultimately, if your DD does not have uniform/equipment/etc the teachers will give her consequences (because that is the school behaviour policy). It's a good idea to try to teach your DD some polite forms of words to deal with this as I can guarantee the teachers will see her as very rude.