This is a beginning 2-column proofs activity. I would first introduce the algebraic properties and have the students do some sort of work with matching up steps from an equation with the properties.
This activity can be done individually or with a partner. I do partners and it works out great. There are three algebraic two-column proofs where I have mixed up the statements and reasons. The students cut them apart and then glue them back together on notebook paper in the correct order in the 2-column format.
**A good tip here is to copy the three proofs onto different colored paper. That way any group that gets scissor-happy and cuts them all apart at once can keep the three proofs separated.
I like to introduce two-column algebraic proofs first in my geometry class. Students are pretty familiar with solving equations by this time, so the 'statements' side of a two-column algebraic proof is pretty easy for them. This way they get practice using the algebraic properties as their 'reasons' as well as getting their first look at two-column proofs.
I think this is most relevant to a high school geometry class, but could be easily integrated at the 8th or 9th grade level when teaching equations, as an intro to proofs they will see in the future.