There are three significant parts of chapter 11 in The Giver. In the first part, The Giver shares his first memory with Jonas.
This first memory is one of sledding down a snowy hill. Because of climate control in his community, Jonas has never experienced snow. He enjoys the fun sensation of sledding and the feeling of the snowflakes on his skin.
The next part of the chapter is when the Giver explains why there is no more snow. He tells Jonas that climate control was created in part for the growing of crops. He also shares a memory of laying in the sunshine with Jonas.
The last part of the chapter is when Jonas asks the Giver what he should call him. "'It's just that I don't know your name. I thought you were The Receiver, but you say that now I'm The Receiver,'" Jonas explains. It is then that his new teacher tells Jonas that he should call him "The Giver."
If you are looking to write a three sentence summary of this chapter, you will have to choose which information is most important. You may decide to focus on one part or have a sentence for each of the three parts.