Students created number trains with linking blocks. I had students sit in a circle as I poured out hundreds of linking blocks onto the carpet. I would yell a number and partners had to make as many number trains as they could that equaled the number that I yelled out.
Students then were given a number and had to make as many number trains as they could that equaled the number I gave them. When they finished their trains they took a picture and tweeted it out.