#### Topic: Differentiate between circle, oval and semi-circle shapes

“Such a dull day!” says Cirho. All four of them are bored. They want to do something exciting and fun. They decide to visit Uncle Math.

“Good afternoon!” they wish altogether. Uncle Math is surprised to see them. “We were so bored today, so we thought of visiting you. Why don’t you give us some exciting task?” says Squarho. Uncle Math smiles and says, “How about a car making challenge? Sounds exciting enough?” The kids are thrilled.

“But what we have to do?” questions Cirho. “First, you need to draw car models on paper. Later using Mr Real gadget, we will convert your drawings into real cars. The most unique and pretty car model will win”, explains Uncle Math. The kids are super excited and all are set to participate. Cirha and Cirho form a team. Triho and Squarho decide to participate alone.

Triho draws a red car. Squarho draws a blue car. Cirha and Cirho draw a green car. Now it is time to add wheels to their car models.

Cirha and Cirho decide to make round circular wheels. Looking at them, Triho says, “They are making circular wheels. If I copy them, my car won’t be unique. I will make oval shaped wheels”. Looking at Triho, Squarho says, “I need to make different wheels too. I will make wheels in semi-circle shape”. Soon they begin making their wheels.

It is showtime! Uncle Math asks the kids to reveal their innovative cars. Squarho goes first. He proudly presents his blue car with semi-circle wheels. Uncle Math grabs Mr Real gadget and says, “Convert the drawing into a real car. Go!” As the light from the gadget falls on the drawing, it turns into a beautiful car.

It is time to see if Squarho’s car really works. When asked to move, Squarho’s blue car does not go ahead much. He is disappointed.

Triho goes next. He shows his beautiful red car with oval wheels. Mr Real gadget works like a trick again. The car looks amazing! Yay!

Triho’s car moves, but with a lot of jerks. He is disappointed too.

Finally, Cirha and Cirho show their pretty green car with circular wheels. Mr Real gadget turns their car into a real one.

When Cirha and Cirho move it, their car moves smoothly. Hurrah! They jump out of joy.

Uncle Math is impressed by all three cars. All the ideas are unique in their way, but only one is right. Can you guess who won the challenge? Yes, Cirha and Cirho. But why? Triho and Squarho are upset.

“My oval shape also looks like a circle. Why did my wheels not work?” questions Triho. “An oval shape is an elongated circle. It is like a circle pulled from two sides. Thus the distance between a point on the border and the centre is not equal. Hence it cannot roll properly”, explains Uncle Math.

“What about my semi-circle wheels?” questions Squarho. “Look at your semi-circle carefully. It is straight on one side and curved on the other. It will easily move on the curved side and will stop on the straight side”, explains Uncle Math.

“The circular wheels of Cirha and Cirho’s car will roll well as a circle is made up of points that are at equal distance from the centre”, he explains. The kids now understand the difference between oval, circle, and semi-circle.

“All your cars are very unique. It is not just about innovative ideas but also about what is usable and what is not. Always remember this!” says Uncle Math. The car models taught them their first business lesson.

## We Learnt That…

• A circle is made up of points that are equal distance from the centre. It rolls well.
• An oval is longer than a circle, it rolls but with jerks.
• Semi-circle has one straight line and one curved line.
• It is not just about innovative ideas but also about what is usable and what is not.

## Let’s Discuss

• What challenge does Uncle Math propose?
• What types of cars did we make?
• How did we convert our drawings into cars?
• Why could only Cirha and Cirho’s wheels roll? Why not ours?