2D shapes are also called two-dimensional shapes, polygons or flat shapes. These are the first shapes that children learn. Children as young as 2 years of age can begin recognizing simple 2D shapes, such as circles, and drawing them.
Learning 2D shapes is key for future math learning. If students don't recognize 2D shapes, they won't be able to recognize 3D shapes and will not be able to handle geometry. Knowing 2D shapes is also important for measurement, as students who can't recognize a rectangle won't be able to measure it correctly. The shapes also help students learn vocabulary words like "side,” "corner,” "angle,” "vertex,” "straight" and "line.”
In addition to being vital to math learning, 2D shapes are important for art and life skills. Shapes are the basis of many early drawing and painting lessons, as well as being a handy way for non-artists to draw recognizable objects like stick people (circles and lines) and houses (a triangle on top of a square). Students, when filling out forms and taking standardized tests, must "check the box" or "fill in the circle" to answer. Students who can't associate the 2D shape with its written name will have a hard time completing these tasks.
2D shapes are those shapes that can only be measured by height and width; they have no depth. Usually, they are pictures in books or shapes drawn on a page, although very flat objects like signs can also be described by 2D shape names. Shapes of physical objects like blocks or books are 3D shapes because they have depth as well as height and width.
To learn to identify shapes, students must see examples of them. Simple pictures of each 2D shape by itself, or with its name underneath, need to be shown to the students so that they can really see their outlines. Teachers or parents should discuss with students the characteristics of each shape, including how many sides it has, how many corners, whether all the lines are straight or curved, whether all the sides are the same. Students can start by learning the shapes that are easiest to distinguish: the circle, triangle and square. Next, they can move on to rectangles, ovals and pentagons. Students should also learn about hexagons, octagons, parallelograms and any other 2D polygons listed in their states' math standards.
After students have been introduced to 2D shapes, they should complete activities to solidify their knowledge. They should search for 2D shapes in the world around them, draw using them, sort them into different categories, create patterns with them and match 2D shapes with 2D shapes of different sizes, angles or colors, such as a small right triangle with a large one.
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