One possible version:

The students in our class took part in an activity of  "Experience a Low-carbon Day" during the Labor Day vacation．In the morning, we went to parks by bus instead of going by car．At noon, when we dined out in a restaurant, we refused to use the disposable chopsticks served there．Instead, we each took with us a lunch box in which there was a pair of chopsticks and a spoon．In the afternoon, we went shopping at a supermarket．To avoid the damage the free plastic bags caused to the environment, we put what we had bought into cloth bags．It was hot at night．We didn't turn on the air conditioners．We used electrical fans to cool ourselves down．

Although the activity lasted only one day, we have learned a lot from it．We realize that we should take actions for our earth from the small things around us．In this way, we are sure to live in a better world．