![]() ![]() But unlike its rocky siblings, almost 70 percent of Earth's surface is covered in oceans of liquid water that average 2.5 miles deep. Like Venus and Mars, Earth has mountains, valleys, and volcanoes. On land, the continental crust is an average of 19 miles thick, but the oceanic crust that forms the seafloor is thinner-about three miles thick-and denser. Beyond the outer core lies the mantle, a 1,800-mile-thick layer of viscous molten rock on which Earth's outermost layer, the crust, rests. The inner core is surrounded by the outer core, a 1,400-mile-thick band of iron and nickel fluids. ![]() Over time, Earth's interior-which is made mostly of silicate rocks and metals-differentiated into four layers.Īt the planet's heart lies the inner core, a solid sphere of iron and nickel that's 759 miles wide and as hot as 9,800 degrees Fahrenheit. Many layers, many featuresĪbout 4.5 billion years ago, gravity coaxed Earth to form from the gaseous, dusty disk that surrounded our young sun. On two specific dates each year-called the equinoxes-both hemispheres get illuminated equally. In the spring and fall, each hemisphere receives similar amounts of light. Whichever hemisphere is tilted closer to the sun experiences summer, while the hemisphere tilted away gets winter. This axis of rotation is tilted 23.4 degrees away from the plane of Earth's orbit around the sun, giving us seasons. Astronomers define this distance as one astronomical unit (AU), a measure that serves as a handy cosmic yardstick.Įarth rotates on its axis every 23.9 hours, defining day and night for surface dwellers. During this circuit, our planet is an average of 93 million miles away from the sun, a distance that takes light about eight minutes to traverse. Though we can't feel it, Earth zooms through its orbit at an average velocity of 18.5 miles a second. Since our calendar years have only 365 days, we add an extra leap day every four years to account for the difference. Our dance around the sunĮarth orbits the sun once every 365.25 days. Find out the origins of our home planet and some of the key ingredients that help make this blue speck in space a unique global ecosystem. PS – For another, more advanced look at division and sharing, consider “The Lion’s Share”, also by Matthew McElligott.Earth is the only planet known to maintain life. The next post contains some of the key images from the book so you can project them for your students to view and discuss.ĭon’t forget to play “The Game of Remainders” as follow up! Rules can be found by clicking here: It inspires interesting conversations about doubles, groups of and division with remainders… I ask that learners copy the pictures on key pages, then record what a mathematician would write for that particular image. “Bean Thirteen” is a story about 2 crickets who gather beans to eat, but find that, no matter how they share them, or with how many friends, there is always one left over! The story makes an excellent read aloud, and the pictures are worth sharing with students of all ages. He is a mathematically clever author whose stories play with important concepts in accessible ways. One of my all time favourite stories for introducing division is “Bean Thirteen” by Matthew McElligott. All other line masters are included and are to be copied onto black and white, but these ones deserved a little colour…! ![]() PS – Please click below to download select colour line masters drawn from the resource. If you’re interested in getting your hands on a copy, click here to order online. Select lessons are suitable for kindergarten students as well.Ĭost for the resource is $40 plus shipping. Matched to the WNCP and BC math curricula, this book is designed for classroom teachers of grades 1 to 3 and primary resource teachers. Organized by strategy, these lessons are designed to promote mastery of the facts, not just memorization! Teacher tips for using and organizing manipulatives, for supporting students who struggle and for working in a combined grades setting are also included.
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