Acute triangle is a triangle in which all of its angles are acute angles. Obtuse triangle is a triangle in which one of its angle is obtuse angle. Students are asked to measure all angles of a triangle, and will find out the sum of the measures of the angles of a triangle is 180 o . Demo of constructing an isosceles triangle is directly to help children construct an isosceles triangle with compass. Quadrilaterals Square is a quadrilateral having four congruent sides and four angles of equal measure.
Parallelogram is a quadrilateral in which the opposite sides are congruent and parallel.
Trapezoid is a quadrilateral in which one and only one pair of sides is parallel. The distance around a circle is called the circumference of the circle. Student can cut off the triangle and place it to the other side of the parallelogram to form a rectangle. Finally, student will be able to find out the area of a parallelogram is equal to the length times the width. To have student cut a triangle and trace it for another.