"Their teacher has very high standards."
Transliteration is: "Their teacher's demands are high". Google translates “他们的老师要求很高” to "Their teachers are very demanding". As “要求” is a word we learn in this lesson, and as it actually translates to "claim", "demand" or "mandate" according to Google, it seems better to me to use Google translation as it does not alter the newly taught word meaning. Thereby, one wouldn't be surprised when "request" is supposed to be translated as “要求” in another exercise of this lesson.