Lines and Angles: common misconceptions

If your child says… “Ray AB and ray BA are the same.”

Ask together

Which starting point does each name give?

What’s true

Reversing the letters changes the ray's starting point and direction.

If your child says… “I can put the corner letter anywhere.”

Ask together

Which letter do both paths, A–B–C and C–B–A, pass through?

What’s true

The corner's letter belongs between the other two letters.

If your child says… “Longer arms make a bigger angle.”

Ask together

Where is any extra turn when both arms overlap?

What’s true

Extending a drawn arm without turning it leaves the angle unchanged.

If your child says… “Exactly half a turn is obtuse too.”

Ask together

At half a turn, do the outer arms still bend or form a straight path?

What’s true

Half a turn is straight, marking the boundary between obtuse and reflex.

If your child says… “Four equal turns means four degrees.”

Ask together

How many degrees must each equal turn contain to total 360°?

What’s true

Four counts the equal turns here, not the degrees within each turn.

If your child says… “Either number beside the arm will do.”

Ask together

Which scale begins at zero where this arm lies?

What’s true

The correct scale starts at zero on the aligned arm.

If your child says… “Any ray inside an angle is a bisector.”

Ask together

Would unequal openings overlap exactly when folded together?

What’s true

Only a ray making equal halves bisects the angle.

If your child says… “The degree mark finishes the angle.”

Ask together

Where is the second arm joining the vertex to your mark?

What’s true

The mark locates the direction, but the second arm still needs drawing.