Is this/that your...". Around the same time, you'll teach His/Her/Paul's.
This is a sheet I made which covers that in a fun puzzle style.
I actually got the idea for this (although it wasn't their's originally) from JHSEnglipedia. The version on that site is ugly and over complicated. I completely reworked it and the results are what you can download here.
The idea is pretty self explanatory. Give each pair of students one copy of the sheet with the full images (or one each if you want), and one copy each of the answer sheet. Students have to work out what the snippet represents and write the sentence in the box. The lines around different objects dictate their owner, so the first snippet would be "It is Paul's dog." Of course, you can change it to "This is Paul's dog" if that's what you've been asked to do. Both are covered consecutively in my textbook.
As always, this activity is now yours to keep, but please don't redistribute it anywhere else. Link to us!