It's interesting to find out what other students are doing so you may compare and discuss differences and similarities in your educational timetable. However in the UK, the day is usually comprised of a number of different classes during the day when different subjects are covered during the lessons, so a more appropriate question would be:
"What did you do at school today?"
"Oh, we had Maths in the morning, then after lunch, English and PE."
What classes did you do today?
or
How much did you learn today?
"Did you have any good classes today?"
or
"What did you learn today?"
What classes did you do today?
今日は何の授業をしたの？
How much did you learn today?
今日はどれくらい習ったの？
"Did you have any good classes today?"
今日は楽しい授業だった？
"What did you learn today?"
今日は何を習ったの？
What subjects did you learn about during your lessons today?
The noun 'subject' has a couple of meanings, but, in this context, it means 'a branch of knowledge studied or taught in a school, college, or university'. The noun 'lesson' means 'a period of learning or teaching'. Since it is already evident that the person you are asking was at school today, it is apparent that he/she attended lessons there. During the lessons, he/she learnt about some subjects which you would like to know what they were. Were they English, Mathematics, Science etc?
So, you may ask:
What subjects did you learn about during your lessons today?
subjectという単語はいくつか意味がありますが、この場合は科目・学科（a branch of knowlege studied or taught in a school etc.）となります。
Lesson＝授業という意味で、「学習や教える時間」の事を表します。
この場合、すでに相手が学校にいたということですので、「授業を受けた」ということもわかります。授業の中で英語、数学、科学のように何の「科目」「学科」を学習したのかを知りたいのですよね。
What subjects did you learn about during your lessons today?（授業で何の科目を勉強してきたの？）と聞くとよいでしょう。
英会話講師のKOGACHIです(^^)/
おっしゃられている内容は、
What class did you have today?
「今日は何の授業がありましたか？」
のように表現しても良いと思いました(*^_^*)
以上ですm(_)m
少しでも参考になれば幸いです(#^^#)
お困りの時は、いつでも気軽にご質問ください(^0^)/
★★どうぞよろしくお願いもうしあげます★★
see you soon♪
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