In a Shimajiro educational book I saw a line similar to this:
___ちゃんが知ってる乗り物は何ですか？
(the actual one had less Kanji but you get the point)
The question is why was ちゃん used here as a generic term. I thought ちゃん was used more for girls and くん for boys, and since I think the audience for Shimajiro might be more boys, why didn't they choose くん here? Or is ちゃん actually a more neutral term?
It's common to use ちゃん regardless of their sex when they're are very small... roughly under 6 years old or so.
http://oshiete.goo.ne.jp/qa/983087.html
平均的なところでは，
○未就学児は男女問わず「ちゃん」
○小学生～高校生は男子が「君」，女子が「さん」
○大学生以上の学生，社会人（18歳未満でも）は「さん」
○ただし政治面など硬めのニュースでは男女問わず「氏」
さん is the most common courtesy title to be used for both males and females. It’s like Mr., Mrs., and Miss.
ちゃん is more casual and intimate form of さん, which is used between or among close friends and colleagues of both male and female, and notably among children.
But, ちゃん is neither gender or age specific. I’m 83 year-old man and called as "Oishi-san" in most occasions of social association, but still addressed by the pet name of “Yo-chan” at an informal event such as local community activities and high school and college class reunions. In turn, I call my friends back by referring them "XX ちゃん."
I've witnessed some Chairmen and Presidents of big companies were calling their peers by XX ちゃん each other during small talks at buffet parties of business leaders' social gatherings.
君（くん）is used between the persons at exactly same level in terms of social position and status or to one's subordinate(s).
氏 is a formal way of calling the third parties as often found in the reports and articles of newspapers when they refer to a person’s name. When you are involved in a criminal case, you are deprived of the right to be called by honorific title, and simply referred by name only.
