Theory:

     One Sunday when the lady had chained him up as usual and was about half-way through the forest, she suddenly thought she heard the cracking of a tree-branch on the winding footpath behind her. She looked back and was horrified to see the bear coming along full speed. Bears look as if they move along quite slowly but they shuffle along much faster than a trotting horse. In a minute he had joined her, panting and sniffing, to take up his usual place, dog-fashion, at her heels. The lady was very angry, she was already late for lunch, there was no time to take him back home, she did not want him to come with her, and, besides, it was very naughty of him to have disobeyed her. She told him in her severest voice to go back at once, menacing him with her parasol. He stopped a moment and looked at her with his cunning eyes, but did not want to go back and kept on sniffing at her. When the lady saw that he had even lost his new collar, she got still more angry and hit him on the nose with her parasol so hard that it broke in two. He stopped again, shook his head and opened his big mouth several times as if he wanted to say something. Then he turned round and began to shuffle back the way he had come stopping now and then to look at the lady till at last she lost sight of him.
Explanation:
 
The lady chains the bear, just like she chains him on all the Sundays that she visits her sister. But this time, when she is halfway through the forest, she is stopped by a sudden rustling sound of the leaves. She hears the sound of the tree branch cracking behind her. She feels that she is being followed and turns around to see the bear following her. The tree branches were cracked by the heavy body of the bear when he was passing through. His fast pace created the noise that made her look back. In spite of looking clumsy when they walk, bears can move faster than a horse when they want to. He therefore reaches her, panting for breath as he had hurried to catch up with her. He also sniffs for her scent, like a dog who would follow his master at his heels.
 
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A woman walking through forest
 
The lady gets irritated by his presence, since she cannot take him along with her nor go back to the house to take him back. She did not have time to do so, as she was getting late for lunch. Above all, the thing that irritated her the most was the fact that he had disobeyed her orders, broken the chain free and followed her. To vent out this anger on him, she shouts at him for being disobedient and pokes with her umbrella to make him turn back and walk home. But after few minutes of being taken aback by the lady's reaction, he starts sniffing on her again. When she gets angry that he is wasting her time, she notices that he has missed the new collar that she had recently bought. She is even more blinded by her anger and fails to think more. She picks up her umbrella and hits him so hard as a punishment that it broke into two.
 
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Angry woman
 
The bear who was probably not expecting this to happen was taken aback by the lady's actions. He opens his mouth wide in shock, as if he wanted to convey something to the lady, and shakes his head in disbelief. He then decides to quit and return as he did not want the lady to beat him any further. He stops now and then to look back at the lady, as he is still in shock and fear of what had happened and finally disappears into the dense forest.
 
Meanings of difficult words from the paragraph:
 
S.No
Words
Meaning
1
CrackingBreaking
2
FootpathWay through which one walks
3
HorrifiedScared
4
ShuffleWalk by dragging one's feet along
5
TrotFaster than a walk, taking short steps
6
PantingOut of breath 
7
MenacingThreatening 
8
SniffingSmelling by breathing air audibly 
9
ParasolUmbrella 
10
RustlingSoft cracking sound, mostly caused by leaves 
Reference:
National Council of Educational Research and Training (2006). Supplementary. The Bear Story (pp.52-57). Published at the Publication Division by the Secretary, National Council of Educational Research and Training, Sri Aurobindo Marg, New Delhi.