The eighth day of the holiday of Sukkot is actually a separate holiday called Shemini Atzeret. It means "the eighth day of the assembly."
The Israelites gather for seven days around the Temple in Jerusalem, and they are just not ready to go home yet, because they are having so much fun. So they stretch the seven-day holiday into one more day.
These days, Shemini Atzeret is one day long in Israel and two days long outside of Israel. In Israel, the first day of Shemini Atzeret is Simchat Torah (meaning, the Happiness of the Torah). Outside of Israel, Simchat Torah falls on the second day of Shemini Atzeret -- so we actually get nine days of holiday!
I hope you plan on making a beautiful flag that you can wave high above your head when you join the Torah procession. Remember, on this day we finish reading the Torah and we start all over again without even taking a breath! The cycle of Torah reading is like the cycle of the seasons. On Simchat Torah, we also pray for rain. It is time for the rain to bless our earth throughout the fall and winter months so that when the spring comes round again we will be able to decorate our Passover table with colorful flowers!