Looking for recommendations for biographies

I have been so impressed since I joined this writing community in March with the generosity of the members. I have gotten so many supportive, kind, and helpful comments on my posts. So today I'm asking for your help in recommending some books for my 4th grade class.

I'm searching for excellent biographies for upper elementary readers. I would like to use this type of book for use as both mentor texts and for research. One of the writing projects our 4th graders do each year is a research report on a subject related to the American Revolution. Many of the children choose to do a biography. Over the years I have read more biographies of people of that era, both children's and adult's, and I realize that many of the biographies for younger readers are not as engagingly written or, often, even completely accurate or complete.

When I read the post on Two Writing Teachers a couple of weeks ago about the presentation by Ralph Fletcher on teaching authentic nonfiction writing, I realized that this is the type of biography I have been looking for. The kind of nonfiction book that David McCullough writes, for example, but for young readers.

In our research project, we have the students read at least two sources for their topic. One is an
"easy" book, below grade level - a picture book if we can find one. I like the books by David Adler, the series with titles, "A Picture Book of...." This gives the young researcher a quick overview of the entire topic. The second book is generally a short chapter book, which provides more details, and also gives us a chance to teach the importance of more than one source. It's always interesting when students find discrepancies and need to decide how to handle that.

So I am looking for excellent biographies for young readers, about any person not just those from the American Revolution. I'm hoping some of you will be able to give me some suggestions! Thank you for your help!