Sectional interest groups are formed by individuals or organizations that represent a specific section or segment of society. These groups advocate for the interests and concerns of their members, often focusing on specific issues or industries. They aim to protect and promote the rights and welfare of their constituents. Some examples of sectional interest groups include trade unions, business associations, and teachers associations.

Trade Unions:
- Trade unions are formed by workers from a particular industry or profession.
- They aim to protect the rights and interests of their members, such as fair wages, better working conditions, and job security.
- Trade unions negotiate with employers on behalf of workers and may engage in collective bargaining or strike actions to achieve their objectives.
- They often lobby the government for labor-friendly policies and legislation.

Business Associations:
- Business associations are formed by companies and entrepreneurs from a specific industry or sector.
- They work towards promoting the interests and growth of their members' businesses.
- Business associations may engage in policy advocacy, representing their members' concerns to the government and seeking favorable regulations and policies.
- They may also provide networking opportunities, industry research, and resources for their members.

Teachers Associations:
- Teachers associations are formed by educators and teaching professionals.
- They aim to address the concerns and issues faced by teachers, such as professional development, working conditions, and educational policies.
- Teachers associations advocate for improved teaching standards, fair compensation, and better working environments.
- They may engage in collective bargaining with educational institutions or government bodies to negotiate for better terms and conditions for teachers.

In conclusion, trade unions, business associations, and teachers associations are all examples of sectional interest groups. They represent specific sections of society and work towards safeguarding the interests and welfare of their members. These groups play an important role in advocating for their constituents and influencing policy decisions that impact their respective industries or professions.