4.8.A* 4.8.B*

Angles & Lines 4th Grade

Texas Essential Knowledge and Skills (TEKS): 4.8.A*
identify and describe right, acute, and obtuse angles;
Texas Essential Knowledge and Skills (TEKS): 4.8.B*
identify and describe parallel and intersecting (including perpendicular) lines using concrete objects and pictorial models; and

An acute angle is an angle with a measure less than 90°.

A right angle is an angle with a measure of 90°.

An obtuse angle is an angle with a measure greater than 90°.

acute angle	right angle	obtuse angle

less than 90°	90°	greater than 90°

Example:

Angle J appears to be a right angle.
Angle K appears to be an obtuse angle.

Parallel lines are lines which do not intersect.

Perpendicular lines are lines which intersect at right angles.

Intersecting lines are lines which cross or meet at a point.

parallel lines	perpendicular lines	intersecting lines

do not intersect	intersect at right angles	cross or meet

Example:

Line segments MJ and JK appear to be perpendicular.
Line segments JK and KL appear to be perpendicular.
Line segments KL and LM appear to be perpendicular.
Line segments LM and MJ appear to be perpendicular.

Line segments MJ and LK appear to be parallel.
Line segments JK and ML appear to be parallel.

Line segments MJ and MK appear to be intersecting, but not perpendicular.
Line segments JK and KM appear to be intersecting, but not perpendicular.
Line segments MK and KL appear to be intersecting, but not perpendicular.
Line segments LM and MK appear to be intersecting, but not perpendicular.

Angles & Lines

Texas Essential Knowledge and Skills (TEKS): 4.8.A*

identify and describe right, acute, and obtuse angles;

Texas Essential Knowledge and Skills (TEKS): 4.8.B*

identify and describe parallel and intersecting (including perpendicular) lines using concrete objects and pictorial models; and

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