If there is any time left over at the end of the lesson, I would like him to practice writing some English words.
If the lesson finishes a bit early, maybe he could practice writing out a few words in English.
ーIf there is any time left over at the end of the lesson, I would like to have him practice writing some English words.
「もしレッスンの終わりに時間が残っていれば、彼に英単語の書く練習をさせて欲しい。」
I would like to have him practice ... で「私は彼に練習させたい」と言えます。
ーIf the lesson finishes a bit early, maybe he could practice writing out a few words in English.
「もしレッスンが少し早く終わったら、彼は英語でいくつか単語を書く練習ができると思います。」
practice writing out a few words in English で「英語でいくつか単語を書く練習をする」
ご参考まで！
カナダ 
