Make sure your workspace is covered with a drop cloth. Remove any old drywall tape or patches with the scrapper. To remove drywall tape, use the 5-in-1 tool to get underneath the lip of the tape and begin to take the whole strip off.
Next, take the scrapper (5-in-1) tool and rip a gouge in the ceiling just to make the crack a bit wider. This will give the joint compound something to adhere to.
Apply a single strip of drywall tape to the crack. Then, apply the first layer of joint compound making sure to push the mud through the mesh of the tape and into the crack.