一方

The word 一方 can be used to present two contrastive situations or concurrent states, either being used at the beginning of a sentence, or mid-sentence to connect the two ideas. It often translates as something like "on the other hand", "while", or "at the same time."

日本の義務教育は小学校が６年、中学校が３年である。一方、私の国では、小学校だけが義務教育で、中学校からは行っても行かなくてもいい。しかし、ほとんどの子供達は中学校に進学する。
As for Japanese compulsory education, elementary school is six years, and middle school is three years. On the other hand, in my own country, only elementary school is compulsory, and it's okay whether you go to middle school or not. However, almost all children go on to middle school.

カタカナは外国から日本に入ってきた言葉や、動物、花の名前など、特別な名詞に使われます。一方、ひらがなは、助詞や文末、送り仮名などに使われることが多いです。
Katakana is used for words that came to Japan from other countries, for animals, for things like the names of flowers, and for special nouns. On the other hand, hiragana is used a lot for things like particles, sentence endings, and okurigana.

子供達の学力が低下する一方で、受験戦争はますます激しくなっている。
Children's academic ability is declining, and yet at the same time we encourage "examination wars" more and more.

勉強が忙しい一方で、学費のためにアルバイトもしなければならないから、毎日本当に大変だ。
Studying is time-consuming, and yet because of tuition we have to get a part time job, so every day is really tough.