The Senate and House each have an agenda that is prepared for floor sessions known as the Order of Business: House Order of Business | Senate Order of Business
These agendas include lists of bills that may be discussed. The House and Senate have different names for those lists; they also have somewhat different operating procedures.
In the House, the list of bills that are ready for discussion is called the Calendar for the Day. Bills that appear on the calendar are chosen from the House General Register by the House Rules Committee. The bills that are selected from the calendar for discussion may be amended and given a third reading—all on the same day. A noncontroversial bill may be placed on the Consent Calendar.
In the Senate, the process is a bit different. Bills that are eligible to be discussed and amended are placed on either the General Orders calendar or the Special Orders calendar. That decision is made by the Senate Majority leader or their designee.
When discussing bills on the General Orders calendar, the Senate forms itself into what is known as a Committee of the Whole. Bills on General Orders can be amended and recommended to pass. That passage is considered preliminary passage. Those bills are then placed on the Senate Calendar for a third reading and final passage at the next floor session. Bills on the calendar cannot be amended except by unanimous consent. A bill can bypass the General Orders calendar by being designated a Special Order. It can then be debated, amended, and given a third reading, all on the same day.
For more about what's happening in the Legislatures, see our Combined Legislative Meeting Calendar.