What are we to never forget?

Answer From The Annual Reading Schedule - Week 17 Notes For Exodus: That you blot out the remembrance of Amaleq from under the skies (Deuteronomy 25:19). Although this is from another reading, we see this event referenced in Deuteronomy 25 happening in the reading we're in. We get the details in Deuteronomy showing that Amaleq not only fought with them, but attacked the feeble ones in the rear. This could have been referring to Elderly or children, I'm not sure. But we're told in Exodus 17:14 that Yahweh shall completely blot out the remembrance of Amaleq, and so this is something to remember.