In my drive to raise generations of systems thinkers this resource is one of the best! The Waters Center for Systems Thinkers is a wealth of support for systems thinking and application. There are templates and lesson plans and even a great resource bank of simulation games found here.
You can sign up for a free account to get access to all they have to offer and even search by age, topic, tool etc. 
The App for the habits of systems thinker is sensational. You tell me if you want your children to acquire these habits? habits-onepage-2019-cc
They are always adding to this repository of great research, lessons etc and I highly recommend you sign up for both your own learning and for the learning for your students.
What systems resources do you love to use to help students along the journey of complex, interconnected, deep thinking?