Right, acute and obtuse angles

In your book, Maths Mela (Chapter 1), Isha makes corners with two straws. The two straws are like two lines that meet at a point. When two lines meet, they make an angle.

Some angles are right angles, like the corner of a book, a window or a sheet of paper. You can make a right-angle checker: fold a piece of paper in half, then fold it in half again, and the folded corner is a right angle. Hold it against any corner to test it.

An angle that is less than a right angle is an acute angle: it is sharper and narrower than the checker. An angle that is more than a right angle is an obtuse angle: it is wider and more open than the checker. A pair of scissors opened just a little makes an acute angle.

Letters have angles too. V has one angle at its bottom point, and it is acute. A has an acute angle at its top point. Z has two angles, one at each end of its slanting line, and both are acute. L has one right angle. A round letter like O has no angles at all, because it has no straight lines meeting.