Noun:
* Definition: A test, obstacle, or difficulty that requires effort to overcome.
* Examples:
* "The climber faced the challenge of reaching the mountain summit."
* "The company is looking for a new CEO to take on the challenge of expanding into new markets."
* "The students were given a challenge to design a robot that could navigate a maze."
Verb:
* Definition: To invite someone to compete or engage in a test of skill or strength.
* Examples:
* "He challenged her to a chess game."
* "The professor challenged the students to think critically about the topic."
* "The activist challenged the government's policies."
In a Sentence:
The student accepted the challenge (noun) to challenge (verb) the teacher's assumptions about the experiment.