To develop appreciation for mathematics among children, a teacher performs the following activities in the class. Choose the one which is not effective to achieve her objective.

The correct option is: "She always praises the student who achieves highest marks in the class in the term-end examination."

Step-by-Step Educational Explanation:

1. Understanding the Objective:
The teacher's goal is to develop an appreciation for mathematics among all children in the class. Building appreciation involves creating an inclusive, engaging, curious, and collaborative learning environment where students feel motivated to explore mathematical concepts regardless of their test performance.

2. Analyzing the Given Options:

• Option A ("She always praises the student who achieves highest marks in the class in the term-end examination."):
Praising only the top-scoring student creates a competitive environment focused purely on marks rather than deep learning or mathematical curiosity. It can discourage students who struggle or score lower, making them feel unappreciated and alienated from mathematics. Therefore, this practice is not effective for developing widespread appreciation for mathematics.

• Option B ("She shows to children the videos on Indian mathematicians and their contributions."):
This activity inspires students, helps them understand the historical context and rich heritage of mathematics, and fosters interest and appreciation for the subject.

• Option C ("She gives mathematical puzzles and magic squares to be solved in the class."):
Engaging students with puzzles and magic squares promotes problem-solving skills, critical thinking, and joy in mathematical discovery, thereby enhancing appreciation.

• Option D ("She establishes a mathematics corner in her class where students can perform various mathematical activities."):
A dedicated mathematics corner provides hands-on learning, exploration, and practical interaction with mathematical objects, which strongly supports positive attitudes towards the subject.

3. Conclusion:
Among all the options, praising only high achievers in examination scores is counterproductive to fostering a general love and appreciation for mathematics across all learners.