Neutral:
* He was ignorant of the local customs, so he made a few social faux pas.
* The research team discovered that many people were ignorant about the dangers of secondhand smoke.
Negative:
* It's ignorant to make assumptions about people based on their appearance.
* The politician's ignorant comments about immigration were widely condemned.
Positive:
* The child was ignorant of the world's troubles, finding joy in simple things. (Here, "ignorant" implies innocence rather than a lack of knowledge)
Formal:
* The author's ignorance of the historical context made his analysis flawed.
* Despite their ignorance of the subject, the students were eager to learn.
Informal:
* I was ignorant about how to fix a flat tire, so I had to call for help.
* Don't be ignorant! It's common courtesy to hold the door for someone.
It's important to note that the word "ignorant" can be quite strong, so be mindful of the context and tone you are trying to convey.