All of these items contribute to a 21st century education, but two key tools not on this list may be the most powerful learning tools ever devised:

The careful construction of basic questions about our natural world and the imaginative search for accurate answers to them are at the center of the scientific method—our most important innovation for exploring and uncovering new knowledge. For instance, Einstein’s early wondering about what it would be like to travel on a light beam initiated a lifelong search for understanding and led to the greatest discoveries in 20th century physics.

Learning through solving problems goes back much further in time, to the first humans to plant seeds and domesticate animals, ensuring a local supply of food and the beginnings of agriculture. Problems have been the perennial motivators for tool making, invention, religion, laws, science, engineering, business, and the evolution of virtually all our modern technologies and societal institutions.

Thomas Edison’s celebrated year-and-a-half search for the right materials to make an effective incandescent electric light bulb (plus the wiring, sockets, fuses, and generators to go with it) eventually improved the quality of life for most people—although well over a billion people still live without electricity in the 21st century.¹ His passionate and tireless persistence in solving perplexing problems has been the archetype for engineers, technologists, and learners ever since.

Scientists approach the world with questions: Why is the sky blue? What is the smallest particle in the universe? What causes cancer? How does burning fossil fuels affect the climate? They then use a rigorous method to discover and verify answers to their questions—the scientific experimental method.

Engineers and inventors on the other hand are motivated by challenging problems: How can I make this airplane safer? How can we store more data in a smaller space? How can we use the sun’s energy to heat and power our homes? Engineers use a slightly different method to design, build, and test solutions to their problems: the engineering design method.

Though these methods are similar, they differ in the way answers and solutions are devised and tested, as shown in Table 6.1.

Scientists use experiments to test an explanation or hypothesis, and engineers devise prototypes or create new designs to see how well their solution works. Applying both scientific and engineering methods to basic questions and the problems of our times has vastly accelerated the growth of new knowledge, new skills, and the innovations of modern living. Along with the arts and culture, and our evolving social and political structures, science and engineering have propelled human progress.

Questions and problems are also the natural motivators for learning: Why? is a favorite question of curious young children, and persistence in asking why? well into adulthood can lead to deeper insights and to further questions that inspire lifelong searches for answers to mysteries still unsolved. Puzzling problems that demand fresh ideas in the pursuit of new and better solutions can lead to creative, even breakthrough results and have been the source of useful inventions and innovations great and small throughout history.

The journeys to discover answers to why? and to creating innovative solutions to our perplexing how-can-we . . . ? problems are authentic learning adventures—they deepen understanding, hone skills, provide emotional satisfaction (as well as some creative frustration), and reveal new ways to work, learn, and thrive in our world.

Teachers and parents have long known that asking openended questions and posing intriguing problems engage children’s imaginations and help motivate them to explore, discover, create, and learn.

The learning method based on the power of questions is called inquiry-based learning, or just inquiry, and the method that uses the power of designing solutions to problems is called design-based learning, or just design.

Inquiry and design learning methods have been proven to be highly effective in engaging and sustaining learning and deepening understanding, as we discuss in the next chapter. These learning methods, combined with traditional ways of acquiring content knowledge and basic skills—guided by caring teachers and parents and powered by today’s digital learning tools—are at the center of a 21st century approach to learning.

What would a 21st century learning model look like that uses the power of problems and questions—the “Ps and Qs” of engaged learning—to drive deep interest, understanding, caring, and the application of 21st century skills to real-world challenges? One such learning model, based on a human-powered vehicle familiar to all of us, is helping to transport more and more learners and teachers around the globe into the 21st century. We take this learning model for a test drive next.