First it is established that triangles have sides and are measured by interior angles. They belong to categories based on that. The acute triangle is defined, illustrated and explained. There are many exercises helping students remember the attribute...s of Acute triangles as distinguishable from other triangles. Students will use an interactive protractor for practice to correctly measure interior angles to distinguish acute triangles from others.[more]

To a rocking tune of Old McDonald Had a Farm, this video features students singing a simple song that teaches acute, obtuse, and right angles. Students form the angles with their hands. (01:04)

Compare attributes of two-dimensional shapes (square, rectangle, triangle, and circle). Identify the properties of two dimensional figures using appropriate terminology.

This is a rap song about angles. The song explains acute, right, and obtuse angles. The animations of the angles are clear. This would be a fun introduction to angles. (01:56)

This is a video lesson introducing right angles. Larry shows a a picture of a right angle and explains how it is defined and how to recognize it. (01:34)

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