As the school year gets started, one of my first challenges is to learn my students' names. After a few days, I stand at the door and don't let the kids enter until I say their name. I know I'm going to get some of them wrong at the beginning, but it lets the students know that I am working on it and that it's important to me that I learn them. I have heard students in my class say at Christmas that such and so teacher doesn't even know my name. That's not good!
But, as the year goes on, the beginning of class needs some variety. I am not a big fan of Do Now questions - I have never been able to get that to work quite right...but I know that does work for some people. What I like to do is to try to generate some excitement at the beginning of class - make students want to get there on time to see what's going to happen!
A video showing at the beginning of class of some interesting math thing happening is always a big hit. Even if it's not necessarily related to the days lesson, it still generates interest.
I like the idea given in the pin above - give students part of a problem to solve. It would be great if all students had a different part to the problem and all of the parts come together for one big solution. This follows right along with give each student a part of a picture and have all the parts come together for one big picture.
A big scrabble game sounds like a great idea...how could we relate this to math - students are only allowed to spell math related words? I have also made a bulletin board size copy of a math crossword puzzle for students to work on.
Here's a good one...give each student a random number when they enter the classroom. Do something with the numbers during class. For example, everyone with an odd number has to write a problem on the board (or demo on their iPad :) or everyone with a multiple of 3 gets a free homework pass as long as they did today's homework...the possibilities are endless!