I think is going to be A historian for the web site of Sioux tribe of Montana. I hope this is correct.
Start by introducing the idea, as if this person is somebody who doesn’t know much about it. Then give three examples each on how it’s been both positive and negative, then add a transitioning sentence to be able to start your next paragraph.
The vES ending should be added to nouns that end in -f or -fe in their singular form. In that case, the -f or -fe is removed and -ves is added as a plural ending. Examples include: life - lives, wife - wives, knife - knives, wolf - wolves, leaf - leaves. But there are also exceptions, such as belief - beliefs, cliff - cliffs, roof - roofs.