In Marah they receive certain mitzvot . The people complain to Moshe and Aharon that they ate better food in Egypt. Hashem sends quail for meat and provides manna, a miraculous bread that falls from the sky every day except Shabbat. On Friday a double portion descends to supply the Shabbat needs. No one is able obtain more than his daily portion, but manna collected on Friday suffices for two days so the Jews can rest on Shabbat.
Some manna is set aside as a memorial for future generations.
When the Jews again complain about a lack of water, Moshe miraculously produces water from a rock. Then Amalek attacks. Joshua leads the Jews in battle while Moshe prays for their welfare. The world gets smaller every day. One of the fears of living in a global village is that the village store is going to run out of food.