What is summary of the medicine bag?

it is About a Boy called martin that his ancestors are native americans 'Red Indians'. he used to tell untrue stories about his grand pa which he knew from the tv or movies and his friends believed him and thought that his grand pa is amazing

but when his grand pa visited them he was so embarrasses of him because he didn't look like the way he told his friends about. he was very short and had grey hair and he was old two. but when martin's friends visited him to see his grand pa he was so ashamed and he thought that his friends will make fun of him and his grand pa but instead they loved his grand pa and thought that he is amazing and martin was so sad because he was embarrassed of his grand pa, so now he loves his grand pa and says that he is amazing. he learned that he must not be embarrassed of his cultures or traditions. before the grand pa died he gave him the medicine bag.