a. (1-8)--The birth of Yitzchak
b. (9-13)--What Sarah said to Avraham about Hagar and Yishmael
c. (14-21)--What happened to Hagar and Yishmael after Avraham sent them away.
d. (22-32)--The berit between Avraham and AvimelekhPlease have your child read the first 8 pesukim of chapter 21 at home.
This is the link to 1-3, 4-7, and 8 (at Navigating the Bible II--Rabbi Aryeh Kaplan's translation).
If you don't like that website here is a link (chabad.org) to another great resource that has all of the pesukim and it also has Rashi with English translation.
Here are some thought questions you can use to help discuss the pesukim with your child:
1. Notice that in Rabbi Aryeh Kaplan's translation (that's the Navigating the Bible II translation) in the 2nd pasuk it says that Sarah gave birth "at the exact time Hashem had promised." This is a translation of the word Moed which we use to refer to the holidays, as in "Moadim l'Simcha." Why was it so important that Yitzchak was born exactly at the time Hashem had promised?
2. You can ask about the 6th pasuk: Why does Sarah say, "Hashem has given me laughter. All who hear about it will laugh for me.'
3. You can also ask about the 8th pasuk: Why did Avraham make a big/great feast/party when Yitzchak got a little bigger (maybe toddler size--from 2-5 years old--we don't know exactly)?Remember these are just suggestions. The main things is to talk with your child about what he or she is learning in Chumash.
Let me know if you have any questions.
Kol tuv (All the best),
Rabbi Yehuda