Home Models & Strategies ยท Grade 4 Angles: Measuring, Drawing and Adding From the words an angle is built out of to the two angles that add up, by way of the protractor skill the test leans on hardest. Four things to name before you can talk about an angle.Apointlineline segmentraya ray has ONE endpoint; two of them make an angleparallelnever meetperpendicularmeet at a right angleboth describe a PAIR of lines, never one on its owna line runs on forever; a segment stops at both ends; a ray stops at one Points, lines and rays Read this one An angle is the slice of a circle that its two rays cut out.55°the vertex sits at the center of the circle360°180°90°a whole turn, a half turn, a quarter turnone degree is one of 360 equal slicesthat is why a protractor is a half circle with 180 of those slices on it An angle is part of a circle Read this one Angle TUV is shown on the protractor. What is its measure?0180301506012090901206015030180025°120°TVUboth rays crossed the OUTER set of numbersthe angle is the distance between the raysU is the vertex, the letter in the middle120° − 25° = 95°same set of numbers for both rays, every timeplacing it yourself? put a ray on 0 and read onceestimate against a square corner before you read anything Reading a protractor Read this one Measure every angle against a square corner before you touch a protractor.rightexactly 90°straightexactly 180°the two you should know on sightacuteless than 90°obtusemore than 90°compare the angle, never the length of its raysan estimate costs a second and catches a reading that is badly wrong The benchmarks Read this one Draw 70°: the protractor goes on the ray.030609012015018070°1 · draw one ray first2 · put the center hole on its endpoint3 · lay the ray along a zero4 · make a dot at 70 on that scale5 · join the dot to the endpointdrawing an angle is reading one in reverse Drawing an angle Read this one Two angles meeting along a shared ray add to the whole angle.35°?80°the parts add to the whole35 + ? = 8080 − 35 = 45°on a straight line the whole is 180180 − 130 = 50°the shared ray belongs to both angles and is counted once Two angles that meet Read this one