Evelyn blinks rapidly a few times, not quite succeeding at hiding her nonplussed expression. What has this kid been reading???? Because she almost certainly can read, and has been, her vocabulary is excellent. Does she read parenting books for fun?
(Does she know that her parents were neglectful? Did it bother her? Or was she happy to be allowed to run around unsupervised, and is worried now that Evelyn will set limits she doesn't want to follow? ...Evelyn can worry about that possibility if and when it occurs, she's not going to borrow trouble when Miranda has been nothing but polite and lovely so far.)
She spends a moment considering how to answer, but doesn't let the silence stretch out long enough to be an obvious hesitation.
"It may not be what you're used to," she says, keeping your own tone casual as well. "But please don't worry about breaking the rules by accident and getting in trouble - I'm not going to be upset with you for not being able to read my mind. I'll explain all of the house rules - it's not very many, but fostering is a bit different from other parenting, and I have duties to make sure everyone is safe - and your social worker is happy with me, of course. We can go over all the house rules once we're there, but the basics - we don't go into anyone else's bedroom unless they're there and giving permission. I'll never come into your bedroom without knocking, though I will have to come sometimes in to clean." It's part of her fostering agency's "safer caring" policy. "We always give each other privacy in the bathroom - you'll have your own, Jeremy and I both have en-suites. I don't have hard rules about how long showers can be, but if another child is placed with me, then we'll need to talk about sharing."
She tries to think what else this precocious tiny child might be feeling unsure about. "Other than that, I would say 'the obvious' but I'm aware that families are different, and this is just how we do things." Evelyn always tries very carefully not to sound like she's criticizing a child's birth family, which is usually upsetting to them even if the parenting they had at home was objectively terrible. "In my house, we don't use bad language, and we never hit. We don't eat food in our rooms, and we don't steal food or anything else - if you need something, tell me, I have an allowance from Social Services to buy you what you need while you're living with me." She meets Miranda's eyes in the rearview mirror, smiles reassuringly. "And I'm sure this won't come up, because you will be a good girl, but if children break the rules, there are consequences. I take away television and computer time, which in my household is a privilege and not a right, but I will never take things that belong to you, or punish you physically. If you aren't sure of whether something is breaking a rule, ask me, I'm never going to be angry because you asked a question."
She hesitates.
"Also, this might be a bit different from what you're used to with your family, but in my household, six is far too young to be going places alone. I'll never leave you home alone; if I need to duck out for meetings, I'll have another foster carer watch you, or I may need to bring you to their house. You can play in the yard by yourself, as long as I'm home and I know you're there, but you mustn't wander off. If you want to go somewhere, I'm always happy to take you in the car." She smiles. "It's not that I don't trust you to be responsible, but it's a rule I have to follow, because your social worker needs to know that I'm keeping you safe." And hopefully that won't be a problem. She is, again, not going to borrow trouble in advance.