Math for Elementary School Teachers (Geometry)
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- What are the levels of the van Hiele Theory?
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0 recognition
1 analysis
2 relationships
3 deduction
4 axiomtics - perpendicular
- two line segments that form a right angle
- parallelogram
- a quadrilateral that has two pairs of parallel sides
- rhombus
- a type of quad. with four sides of the same length
- trapezoid
- a quad with only one pair of parallel sides
- isoceles trapezoid
- a trapezoid with one pair of parallel sides that are congruent
- line of (axis) symmetry
- similar to a "fold line". (if you were to fold a triangle in half down the center it would have a line of symmetry).
- rotation symmetry
- a figure has rotation symmetry if there is a point around which the figure can be rotated less than a full turn, so that the image matches the rotated figure perfectly. (ex: a hexagon)
- regular polygon (or n-gon)
- all sides and angles are congruent
- vertex (or interior) angle
- formed by two consecutive sides
- reflex angle
- greater than 180°
- supplementary angles
- if two angles add to 180°, they are supplementary
- complementary angles
- if two angles add to 90°, they are complementary
- transversal
- if two lines, m and l are intersected by a third line, t, it is called a transversal
- alternate interior angles (AIA)
- in a transversal, they are the angles that are opposite of eachother on the "inside"
- acute triangle
- a triangle with three angles less that 90°
- equilateral figure
- a figure with all sides the same length
- equilateral triangle
- a triangle with three congruent sides
- kite
- a quad. with two pairs of congruent sides that are adjacent
- isoceles triangle
- a triangle with at least two congruent sides
- obtuse triangle
- a triangle with one obtuse angle (greater that 90°)
- scalene triangle
- a triangle with three unequal sides