All elementary school students in #japan use a Randoseru (ランドセル), a backpack design of Dutch origin.
My friend's kid carries a ton of books!
わすれずに
かぎをしめてね!
あんぜんに気をつけて
いってらっしゃい
Without forgetting
Lock the key!
Be careful about safety
Have a nice day
Mom used only one kanji in this sign: 気. The others were probably deemed too difficult.
https://jisho.org/search/%E6%B0%97%20%23kanji
@codewiz I read the last line as 行ってらっしゃい