Constructivism involves students engaging in higher order thinking skills to problem solve or interact with new knowledge. They are building upon experiences. 

Scaffolding is an educational strategy that borrows concepts of what students know in order to provide familiarity from which a student can build new ideas and concepts. 

Anytime I teach a new concept, I will refer to the "I do, we do, you do" strategy. I did this when I taught gradeschool and I do it now that I teach high school...modeling and referencing schema to produce a desirable outcome. I will assist students and then eventually release responsibility to the student to develop mastery of content. 

This process can occur during a single lesson. For instance, when I ask students to discuss 3 causes of the Revolutionary War. I will provide one, explain how and where I developed the answer. We would then come up with one together and eventually students would use what they know to develop their own ideas. 

Or, the process can take much longer. For instance, when I ask students to write a 5 paragraph essay, I am not expecting the first one to be perfect, but rather I guide them throughout the semester while introducing the concepts of primary sources until they master the concept...usually at the end of the semester.