Grandparents' Day
Preschools may have slightly different names – such as 「祖父母参観」(sofubo sankan) or 「おじいちゃん・おばあちゃんの日」(ojiichan/obaachan no hi) – for Grandparents' Day, a day when grandparents are invited to observe their grandchildren at preschool. After a Grandparents' Day event, you may write about your child's reactions and the grandparents' impressions. You may of course speak to the teachers directly instead of writing in the renrakucho.
The following model contains two "Thanking the School" sections, but you may choose to include just one of them. You may also choose to make just a single comment regarding your impressions and/or your child's attitude.
Model
Conversational flow and useful expressions
Thanking the school 1
Child's attitude, etc.
Impressions
Thanking the school 2
Parent's name
Supplement
「お世話様でした」(osewa sama deshita), which conveys a sense of indebtedness and gratitude, is an expression used to say "thank you". When「お世話になりました」(osewa ni narimashita) seems overly polite and seems to create a sense of distance between you and the other person, "osewa sama deshita" may be used instead.