When I first introduce the concept of using a number line as a tool to add and subtract, we pretend that we are frogs and hop forwards and backwards. We go outside and I tell them to add 1 (they hop forward 1), subtract 3 (they hop backwards 3) etc. Then we use sidewalk chalk to make number-lines. After making our number-lines, we act like frogs again and hop forwards and backwards on our chalk-drawn number-lines. They love this activity.
Now, I have always had the idea in the back of my head to find my own little frogs the students could use in class while they use their number-lines...but no luck....UNTIL, a few months ago while shopping in Walmart for party supplies, I FOUND THEM!
We also play a game where all students start their frog on zero and I tell them to add 4 (hop forward), subtract 2 (hop backwards), add 7, subtract 2 etc. The students' goal is for their frog to land on the correct number. They love this game. It is great if you have some spare time.
I hope this gets you excited about NUMBER LINES!