I started a new unit in Geometry- Parallel and Perpendicular Lines. I started with a card sort. I numbered the back of the page going across 1-12. Then I copied each page on a different color of card stock and cut those in half. I passed it out to the students and had them cut out the individual squares. (Yay for student labor!) Unfortunately, when they cut, the numbers were cut in half which posed some problems. Maybe you should have students number them after they cut? Not sure what happened on my end.
I asked students to sort into groups. Some students sorted the ones with fractions, parentheses, and neither. I'm sure you will see a wide variation. The first hint I gave was that students should have three groups. They resorted and I went back around the room to observe. Next, I told them they would have one group of six and two groups of three. From here, almost everyone had their cards in the correct group.
I displayed this slide to make sure everyone had the correct groups.
A few students recognized that the one group of six were in slope-intercept form. Yay for Algebra I. I asked them to put those six cards back into their envelope. Then I passed out this worksheet and asked students to write in the equations on the cards onto the worksheet and solve for y. They did okay at this. After they were done I told them to get the six back out of the envelope because these were the answers to the top of their worksheet. See what I did there?
From there we went to the bottom half of the worksheet which was graphing lines on the calculator. Then on the back we worked down each column individually. We solved a pair of equations for y. We graphed. We noticed both lines were parallel. We compared the equations. Oh my, they have the same slope! We did this three times and summarized that all parallel lines must have the same slope.