Teaching method- It is the strategy approached by the teacher for delivering course material in a way that keeps students engaged and allows them to practice different skill sets. It involves lectures, field visits, discussion methods, etc.Field trip- It is a visit to a location outside the classroom where students can try new things, have new experiences, and obtain first-hand observation.It develops observation and perception skills and also promotes the personal and social development of children by providing hands-on experience.Nivedita can take them to some nearby factory area where they can see how waste generation Is causing pollutionBrainstorming is a type of problem-solving method in which children practice and improve higher-order thinking skills.It encourages creative thinking in students and encourages them to share their ideas.Urban area children will share their ideas about pollution and rural children will get an insight.Hence, we conclude that for introducing the concept, Nivedita should use methods B and D only.HintIn the Lecture method, students are often passive learners, as they cannot connect the concept with real life. This method also fails to provide teachers with feedback about the students learning.