Going from No and Frowning to Yes and Smiling

Nellie is a very grouchy and cranky little girl. She hardly ever smiles, and the first word out of her mouth is always 'No', no matter the topic, no matter the question. But after her brother becomes angry with her for being so negative, and starts calling her 'Nellie Minus', Nellie decides she will try really hard to change. Over the next week, Nellie surprises even herself with her positivity, and finally decides she will become 'Nellie Plus'.