This is the 5695th most frequent Japanese word.
そわそわ
Restless; fidgety.
The word "そわそわ" here is used to describe his restless state due to an upcoming event.
彼は発表が近づいてきているのでそわそわしています。
He is restless because his presentation is approaching.
The word "そわそわと" describes the restless way she is scanning her surroundings.
そわそわと辺りを見回しながら、彼女は誰かを探しているようだ。
She seems to be looking for someone, glancing around restlessly.
In this sentence, "そわそわ" conveys the children's excitement and lack of calm due to anticipation.