Exodus 34

22 ¶And thou shalt observe the feast of weeks, of the firstfruits of wheat harvest, and the feast of ingathering at the year’s end.

Leviticus 23

42 Ye shall dwell in booths seven days; all that are Israelites born shall dwell in booths:

43 That your generations may know that I made the children of Israel to dwell in booths, when I brought them out of the land of Egypt: I am the Lord your God.

Here is an explanation from the LDS Institute Manual: The feast of Tabernacles (also called the feast of Booths or the feast of Ingathering) occurred five days after the day of Atonement on the fifteenth day of Tishri, the seventh month of the Hebrew calendar, which corresponds to our late September or early October. The feast of Tabernacles began and ended on a Sabbath and so was eight days in length.

A distinctive part of this celebration was the erecting of temporary huts or booths (succoth, in Hebrew) made from the boughs of trees. The people stayed in these huts for the duration of the feast. This requirement reminded the people of the goodness of the Lord during their forty-year sojourn in the wilderness of Sinai and the blessing that was theirs to live permanently, if they were obedient, in the promised land.

Here is another good article called When Jesus Attended the Feast of the Tabernacles by the International Christian Embassy Jerusalem.

Knish

I found some Knish at Costco that I served to the students. If you can't find any knish, here is a recipe “Gabila’s” Style Potato Knish

There are some great images of booths (sukkah) that I shared with the students from Google images.

and I told them about waving the Arbah Minim which is a citron, a palm frond, three myrtle twigs and two willow twigs. They combine them all together, bless them and then wave them in six different directions. They represent Israel joining together.