Together@Home have a resource to help families explore Justice as a Biblical command. They explain why here: Many of us are struggling to find the right words to respond to the global outpouring of pain and anger following the death of George Floyd. These are big topics to unpack and discuss with adults let alone children.
However, our God is a God of Justice and we are called to “walk justly” in this world.
Here is a resource exploring what the Bible says about Justice which I hope can be a helpful starting point for you.
Together@Home also have great Trinity Sunday Resources. we have put some resources here but as always, there is more to glean from their FB page and website.
ROOTS have created a helpful prayer resource for difficult times World Ablaze -Prayers for Difficult Times ROOTS
Their resources for Trinity Sunday are here: Sharing The Bible Passage and An Activity ROOTS For families
What is a Trinity: ‘What’s in the Bible’ short video explores the Trinity.’ https://www.youtube.com/watch?v=n-1AdUwbWLw
Julie Currie gives an All Age Talk with props for Trinity Sunday: https://www.facebook.com/JIGSAWDDYC/videos/273617623835459/
Object lesson: Make Playdough together and use the three ingredients to explore the Trinity. God is the pure flour; Jesus is the Salt; and the Holy Spirit is the water: https://www.christianitycove.com/object-lessons-for-sunday-school-understanding-the-trinity-0603/908/
If you want to focus on the names of God rather than on 3-in-1 objects: http://worshipingwithchildren.blogspot.com/2014/05/year-trinity-sunday-first-sunday-after.html
There are some useful diagrams in this for little minds (and grown up minds) that may find the concept of the Trinity confusing. Explaining the Trinity to a 7 year old: https://www.thegospelcoalition.org/blogs/justin-taylor/explaining-the-trinity-to-a-seven-year-old/