Daniel HeckDaniel Heck is Vice President of Horizon Research, Inc. in Chapel Hill, North Carolina and is a Principal Investigator in Project AIM. His research and development work spans many areas of mathematics education: classroom learning environmentsand discourse; teacher professional development design, enactment, and impacts; curriculum design and enactment; and student problem solving. Tying all of this work together is a central interest in how teaching and learning in school can tap into students' intuitions, informal ideas, and insights to develop powerful, formal understandings of mathematics. He has enjoyed and benefitted from collaboration with colleagues in practice and research locally, across the country, and around the world who share this interest.