Densha-ni noru kawari-ni, futaeki aruku koto-ni shita-no. (Instead of riding the train, I've decided to walk (the last) two stations.)

Situation 1: Ms. Gray and her colleague Ms. Tamachi are chatting about diet.

グレイ: 最近、ダイエットが続いているみたいね。

田町: うん。会社の帰りに電車に乗るかわりに、2駅歩くことにしたの。そうしたら、体重が減ってきたのよ。

Gurei: Saikin, daietto-ga tsuzuite-iru mitai-ne.

Tamachi: Un. Kaisha-no kaeri-ni densha-ni noru kawari-ni, futaeki aruku koto-ni shita-no. Sō-shitara, taijū-ga hette-kita-noyo.

Gray: It looks that you're continuing the diet, right?

Tamachi: Yeah. When I go home, instead of riding the train I've decided to walk the last two stations. If I do that, I'll lose some weight.

Today, we will introduce かわりに and かわって, which both indicate an exchange. XかわりにY expresses that someone does Y instead of X. Y is the thing that makes up for X. X is a noun + の or the noun modifying form of a verb or adjective. Examples: バターのかわりにオリーブオイルを使(つか)った (I used olive oil instead of butter.) 本田(ほんだ)さんのかわりに私(わたし)がBC社(しゃ)へ行(い)くことにした (I decided to go to BC-company instead of Mr. Honda.) XのかわりにY is used to show the compensation as in 仕事(しごと)を手伝(てつだ)ってもらったかわりに、ごちそうをするよ (I'll treat you in exchange for your help of my work.) Furthermore, XのかわりにY shows both sides such as advantage and disadvantage of something contrastively. Example: このヒーターは便利(べんり)で安全(あんぜん)なかわりに、電気代(でんきだい)がかかる (While this heater is convenient and safe, it consumes much electricity).

Situation 2: Mr. Shiba arrives at a nursery school to pick up his child.

保育士: あ、きょうは、お父さんがいらしたんですね。

芝: はい、きょうは妻にかわって私が迎えに来ました。

Hoikushi: A, kyō-wa, otōsan-ga irashita-n-desu-ne.

Shiba: Hai, kyō-wa tsuma-ni kawatte watashi-ga mukae-ni kimashita.

Nursery teacher: Oh, Dad came here today.

Shiba: Yes, I came instead of my wife today.

XにかわってY expresses that subject Y does something instead of X. This pattern is used when X is a noun only. Examples: 社長(しゃちょう)にかわって私(わたし)がお礼(れい)を申(もう)し上(あ)げます (In place of our president, I'd like to express our gratitude.) 最近(さいきん)は、携帯電話(けいたいでんわ)にかわってスマホが多(おお)く使(つか)われている (Nowadays, smartphone is often used in place of cell phone.)

Bonus Dialogue: Continued from Situation 1.

田町: ふつうのパンを食(た)べるかわりに、フスマパンを食べることにしたの。そしたら、体調(たいちょう)もよくなったみたい。

グレイ: すごい。今回(こんかい)はダイエット、きっと成功(せいこう)するね。

田町: うん、そんな気(き)がする。

グレイ: たしかに田町さん、ウエストも細(ほそ)くなったみたい。

田町: でも、ひとつ心配(しんぱい)があるの。

グレイ: 何(なに)?

田町: お正月(しょうがつ)になったら、おもちを食べなきゃならないでしょ。それで悩(なや)んでいるの。

グレイ: いやだ。そんなの、食べなくてもいいじゃない。

田町: だめよ! お正月は絶対(ぜったい)におもちを食べなきゃ。食べなかったら、お正月の気分(きぶん)になれない。

グレイ: ふうん。田町(たまち)さんはまじめなかわりに融通(ゆうずう)がきかないなあ。

Tamachi: I decided to eat bran bread instead of the usual white bread. In doing that, it seems my health improved.

Gray: That's amazing. You'll surely succeed with your diet this time.

Tamachi: Yeah, I think so.

Gray: You're certainly losing fat around your waist.

Tamachi: But, there is one thing I'm a little worried about.

Gray: What?

Tamachi: I have to eat rice cakes at New Year's. I'm worried about that.

Gray: Ugh. You don't have to eat them.

Tamachi: No good! By all means, I must eat rice cakes during New Year's.If I don't eat just one, I won't be able to get into the spirit of the New Year's holidays!

Gray: Hmm. Ms. Tamachi, it seems you're a bit inflexible rather than being the serious person (that I thought you were).