This book’s history stretches back 50 years when, in the 1960s, Seymour Papert presented a bold new vision of how computers might enter the lives of children. At the time, computers still cost tens of thousands of dollars, if not more.The first personal computers would not become commercially available for another decade. But Seymour foresaw that computers would eventually  become accessible for everyone, even children, and he lay the intellectual foundation for how computing could transform the ways children learn and play. While other researchers imagined that  computers might some-day be used to deliver information to children or pose questions to children, Seymour had a very different vision. He believed that children should be in control of  computers, using them to experiment, explore, and express themselves. Seymour and his colleagues at MIT developed the programming language Logo specifically for children so that children  could program their own pictures, stories, and games. In his 1980 book Mindstorms: Children, Computers, and Powerful Ideas, Seymour argued that children should program computers, not the  other way around.
The two of us writing this book (Marina and Mitch) worked closely with Seymour when we were graduate students at MIT,and we were deeply influenced by his ideas. Both of us have dedicated  our careers to extending Seymour’s work, providing young people with opportunities for designing, creating, and inventing with new technologies.
Mitch’s Lifelong Kindergarten research group at the MIT Media Lab collaborated closely with the LEGO Group on the MINDSTORMS and WeDo robotics kits and cofounded the Computer  Clubhouse Network of after-school learning centers for youth from low-income communities. More recently, the group developed the Scratch programming language and online community,  which is used by millions of young people (ages 8 and up) around the world.Marina’s Developmental Technologies (DevTech) Research Group at the Eliot-Pearson Department of Child Study  and Human Development at Tufts University has focused on early childhood learning, developing technologies and activities for preschool, kindergarten, and early elementary students. The group developed the ideas and prototypes that led to the KIBO robot kit, which enables young children (ages 4–7) to program robotic projects by putting together sequences of wooden  blocks.With KIBO, children learn programming without screens or keyboards. In 2013 Marina co-founded KinderLab Robotics to make KIBO widely available. The ideas underlying Marina’s and  the DevTech Research Group’s work are described in Marina’s books Blocks to Robots: Learning with Technology in the Early Childhood Classroom (Teachers College Press, 2007) and Designing Digital Experiences for Positive Youth Development:From Playpen to Playground (Oxford University Press, 2012).In 2010, Marina suggested that our two groups work together to  develop a programming language for young children, extending MIT’s work on Scratch and drawing on Tufts’ experience with early childhood learning, and thus the idea for  ScratchJr was born. We teamed up with Paula Bontá and Brian Silver man of the Playful Invention Company (PICO), who brought strong expertise in the design and development of  programming languages for children (and who also had worked closely with Seymour Papert). ScratchJr has been a true team effort, with contributions by many people at Tufts, MIT, PICO, and  else-where. We encourage you to look at the ScratchJr website (http://www.scratchjr.org/) for a full list of contributors. We’ve been thrilled by the response to ScratchJr from thousands of  children, parents, and teachers around the world, but we recognize that more and better support materials are needed to help people use ScratchJr to its full potential. We wrote this book to  support the use of ScratchJr in both homes and schools. We hope that you find the book useful, and we look forward to hearing your feedback and suggestions.

We want to thank members of the ScratchJr team who helped in researching, writing, and producing this book, particularly Claire Caine, Amanda Strawhacker, Mollie Elkin,Dylan Portelance,  Amanda Sullivan, and Alex Puganali.We are also extremely grateful to Tyler Ortman and Serena Yang at our publisher, No Starch Press. They have provided invaluable help and advice  throughout the process of writing and publishing the book.
ScratchJr would not have been possible without generous financial support from the National Science Foundation (grant number DRL-1118664) and the Scratch Foundation. If you enjoy this  book and ScratchJr, we hope you’ll consider making a donation to the Scratch Foundation (http://www.scratchfoundation .org/) to support the future development of ScratchJr software and  educational materials.