My favorite books to read at the beginning of the year are Have You Filled a Bucket Today? and Bucket Filling A to Z, both by Carol McCloud.
Each of these books does a great job explaining how each of us has an invisible bucket that we carry around each day. When others are kind to us, it fills up our buckets. When we are kind to others, it fills up their buckets. However, when we are unkind to each other it dips into a bucket. Across the lower grade levels, I did a variety of lessons and activities to help students learn about bucket filling behaviors.
We sorted behaviors into Bucket Fillers and Bucket Dippers choices:
We drew pictures to show us being Bucket Fillers:
We made Bucket Filling acrostics using our names:
We sorted choices we make that show others we are Bucket Fillers or Bucket Dippers: