Number Line Activity

Last week I developed a lesson for the seventh grade math class I'm assisting.  I had to fit the lesson between homework review and a quiz so I only had a 20 minute window to improve the students' conceptual understanding of the addition and subtraction of integers.  I heard about a walking number line in class a few weeks prior and I was really excited about the concept as I liked the idea of getting the students to physically act out the process of addition and subtraction.  However, given my time restraint, I didn't think I could develop a meaningful activity for the students in which they could all get up and walk up and down a number line.  So, after searching online, I found a blog-post about a teacher who minimized the idea of the walking number line so each student could visualize it on their own desks.  She accomplished this by creating a desk-sized number line and providing a little stick figure man for each student.  I used this template to develop my own activity.
So, after the students went over their homework, I began by reviewing what they already knew about the addition and subtraction of integers by asking one student to give me an addition problem, and another to answer it.  After we did a couple of these to remind students of what they learned, I began my activity, offering that it would give them some extra help before their quiz.  I explained that the stick figure they all had could be used to walk up and down the number line.  The figure would start wherever the first number is and then face the positive side for an addition problem or the negative side for a subtraction problem.  Lastly, the figure would walk forward the number of steps indicated by the second number.  If the second number was negative, the figure would walk backwards.  The number the figure ended on would be the answer to the problem.  Once they were finished, I would go over the answers and ask the class if they had any questions on any of them.
What I learned from this activity was the importance of checking students' understanding as I taught.  I feel like some students didn't fully comprehend the concept of the walking number line.  A solution would be to have a couple students come up to the front of the class and demonstrate how to solve a problem using the method I described.  This would allow me to walk students through the process, explaining common misconceptions in a way the whole class may see.  Further, if students still had questions after I explained the process to the whole class a few times, I can call on students who seem to grasp the concept to answer these questions to develop a student-centered discussion.
Additionally, I felt like I could have improved my timing and clarity in teaching this lesson.  I felt like it was a great educational experience for me and I know the experience helped me as the lesson went more smoothly and effectively after each hour that it was taught.  Furthermore, it was a great way for me to see visualize where my strengths and weaknesses currently are in my teaching.