Course Guide - USAID Teacher Education Project

2. How do children think about these concepts?a) Seeing angles: Although children may notice angles in their every day experience,they may need to be alerted to what they informally know.For example, young children may walk down a street and see right angles in the streetsigns or in buildings. What about right angles in fabric? Why are right angles soprevalent in the man-made world around us?What about the branching of trees as shown above? Or the movement of a clock'shands around a dial?How can teachers help children notice and name the angles that are in their everydayenvironment?b) Angles are the space between two rays or line segments that meet at a vertex.Children often incorrectly assume that the longer the line segments, the bigger theangle. This is because up to now children's experience with the words "bigger" and"larger" related to linear (1-dimensional) or area (2-dimensional) measurement.If the following two triangles were drawn on a grid, the area covered by each angle inthe first triangle would be "bigger" than the area covered by the second triangle'scorresponding angles.Applying their prior knowledge about size to angles, it is logical for children toassume that the angles in the first triangle below are "bigger" than the angles in thesecond.It requires a major shift in their thinking so that children can begin to consider a newkind of measurement (degrees) and a new definition of "bigger."To help children understand this, they can cut out two similar triangles and lay thecorresponding angles atop each other. They will see that the angles match upperfectly to each other and are therefore the "same size"—in degrees.