Meeting students' individual learning needs has never been easy and seems to only become more challenging with the passage of time. Teachers today struggle to keep up with society's expectations. It isn't enough for them to just cover their curriculum. They are expected to differentiate their instruction, address students' social and emotional challenges, close achievement gaps, address bias and discrimination, and ensure all students are prepared for life in the 21st century. It's hard to imagine teachers measuring up to these goals just by getting better and working harder. Fortunately, what makes personalized learning today different than efforts to personalize in the past is the role technology can play in making personalized learning possible at scale. A key way to unlock teachers' capacity comes from using technology to take lower-order work off teachers' plates. From the wheel, to the steam engine, to the supercomputer, technologies expand what people are capable of producing. Food, clothing, housing, energy, and entertainment are all far more affordable and accessible than they were just a few generations ago because technology has steadily pushed out the frontier of human productivity. Technology can play a similar role in education. With a boost from education technology, teachers can use their time, attention, and energy in new ways to make a bigger difference for their students. This article discusses what technology can and cannot do to improve teacher effectiveness.