• 児童じどう — children (esp. in school)
• 小児しょうに — young child; infant
• 育児いくじ — childcare
• 孤児こじ — orphan
• 幼児ようじ — toddler
• 愛児あいじ — beloved child

児 is the simplified form of 兒, which originally depicted a child with a traditional hairstyle. The radical 儿（ひとあし）suggests legs/a child figure. The character appears widely in words related to young people.

児童じどうは 学校がっこうで 勉強べんきょうします。
Children study at school.

小児しょうにの 病気びょうきに 詳くわしい 医者いしゃが 必要ひつようです。
A doctor with expertise in childhood illness is needed.