Forces can't be seen, but without them, nothing around us would happen! A force is a push or pull that usually causes movement. Friction is a force that opposes motion and slows things down or stops them. Famous scientist and mathematician Sir Isaac Newton wrote the rules about forces and motion.
Alfred Wegener studied astronomy and meteorologyâ€”and was even a record-holding balloonistâ€”before he became famous for his theories on how the land and seas on Earth were formed and change. These ideas are continental drift and plate tectonics. Seeing that the continents fit together like a puzzle, Wegener proved the theory that all of Earth's continents were once connected. Although his theories weren't accepted until after his death, scientists use plate tectonics to explain volcanoes and many other changes on Earth.
British scientist Robert Hooke built an early microscope and was the first scientist to observe cells and give them their name. Anton van Leeuwenhoek created the best microscopes of his time and used them to study living organisms. Matthias Schleiden, Theodor Schwann, and Rudolf Virchow created Cell Theory, which says that all living things are made of cells; cells are the smallest part of a living thing; and all cells come from other cells.
What will houses look like in the future? From space stations to pod living, this innovative title examines how architects design and plan for the world of tomorrow. Readers put concepts to work when they design their own home based around a unique shape.
Ideal for students living in an urban area, colorful illustrations and humorous characters outline the steps needed to build towering homes. Building big and building up, students learn about problems and solutions encountered by engineers and architects.
Explores how human activity affects the Earth, e.g. effects of human activity on groundwater and surface water, habitat destruction, construction, emissions, and pollution.
Pulleys are simple machines used to lift and move loads. Builders use pulley systems to lift tools or materials. Elevators use pulleys to move up and down. Kids will learn how pulleys make work easier and how they are often part of complex machines. Blastoff! Series