Went to see a kindergarden sports day with 運動会

Kanji Explanation: Meeting and joining with 会

Kakeru’s grandmother unexpectedly shows up at the school sports day event.

おばあさん:: 「翔(かける)が幼稚園(ようちえん)の時(とき)一度(いちど)だけ運動会(うんどうかい)を見(み)に行(い)った事(こと)あったわね」; “I went to see your sports day just once when you were in kindergarten, didn't I?”
翔(かける):: 「うん　東京(とうきょう)まで来(き)てくれたよね」; “Yeah, you came all the way to Tokyo for me.”

Key Points

1運動会(うんどうかい) means “school sports day”

運動(うんどう) is exercise or athletics, and 会(かい) is a gathering or organized event.
Here the compound names the school’s sports day, with races and other athletic events.

2運動会(うんどうかい)を見(み)に行(い)った means “went to watch the sports day”

見(み)に行(い)く puts the verb stem 見(み) before に行(い)く to state the purpose of going.
運動会(うんどうかい)を marks what Kakeru’s grandmother went to watch.

3一度(いちど)だけ行(い)った事(こと)あった means “there was just one time I went”

一度(いちど)だけ means “only once”. だけ limits the number of visits.
The fuller form of 行(い)った事(こと)あった is 行(い)った事(こと)があった. Casual speech drops が.
The past あった recalls an occasion from an earlier period.

4東京(とうきょう)まで来(き)てくれた means “you came all the way to Tokyo for me”

まで marks Tokyo as the far endpoint of the trip, giving the sense of “all the way to Tokyo” here.
来(き)てくれた presents the trip as something Kakeru received and appreciated.

5わね and よね make this a shared memory

The grandmother’s わね sounds as though she is recalling the occasion and inviting Kakeru to agree.
Kakeru begins with うん and ends with よね, affirming her memory while asking her to confirm his added detail.

時 (Time)

時(とき) means time, a moment, or an occasion.

運動会 (Sports day)

運動会(うんどうかい) means a school sports day or community athletic meet with races and team events.

来る (To come)

来(く)る means to come or move toward the speaker or the place being discussed.