Meaning: 'Were' is the past tense of 'are,' used to describe a state or action that occurred in the past.

Wrong options:

• had been: This form suggests an action that was completed before another past action, which is not the case here as the ongoing action of the researchers aligns with the simple past.
• has been: This present perfect form indicates an action that started in the past and continues to the present, which does not fit the context of the past narrative.
• are: This present tense form does not match the past context of the sentence, as it implies current action rather than past.

Correct answer: interactions

Explanation: The term 'interactions' is appropriate as it refers to the exchanges between Piaget and young people, fitting grammatically as a plural noun that complements the context of his experiences with children.

Meaning: 'Interactions' means exchanges or communications between people, highlighting the active engagement Piaget had with children.

Wrong options:

• discussions: While 'discussions' could fit, it implies a more formal exchange of ideas, which may not encompass the broader range of engagements Piaget had with children.
• treatments: This term suggests a clinical or therapeutic context, which does not align with Piaget's observational and research-based interactions with children.
• communications: Though related, 'communications' is more general and lacks the active engagement implied by 'interactions,' making it less suitable.

Correct answer: had developed

Explanation: The phrase 'had developed' indicates that Piaget's development of new fields occurred before another past event, which is consistent with the timeline of his research career as described in the passage.

Meaning: 'Had developed' refers to the completion of the action of developing new fields prior to the time of his death, emphasizing the extensive nature of his contributions.

Wrong options:

• has developed: This present perfect form suggests an ongoing relevance to the present, which does not fit the past context of Piaget's career.
• developed: While grammatically correct, this simple past form does not convey the sequence of events as effectively as 'had developed' in this context.
• was developing: This past continuous form implies an ongoing action at a specific time in the past, which does not accurately reflect the completed nature of Piaget's achievements.

Correct answer: championed

Explanation: The word 'championed' indicates that Piaget actively supported and promoted a new way of thinking about children, fitting well with the context of his influence on educational reform.

Meaning: 'Championed' means to support or advocate for a cause, highlighting Piaget's role in promoting new ideas about child development.

Wrong options:

• created: This term implies the act of making something new, which does not capture the advocacy aspect of Piaget's contributions as effectively as 'championed.'
• opened: While this suggests initiating something, it lacks the connotation of active support that 'championed' conveys.
• generated: This term implies producing or causing something, which does not accurately reflect Piaget's role as an advocate for a new way of thinking.