Well, dealing with living organisms (lol) there are going to be variables...no getting around that. And those variables are what makes it interesting. You might even turn those variables into part of your paper...why does one dog respond differently? Was there something diffferent in his early puppyhood perhaps? Is it to do with his breed? Why could that be? Is he more distracted? While they're all domestic dogs, they may vary with some of the tests. You probably should repeat any single test several times so that it can't be thought of as a fluke when they do something. You want to make it a true experiement, and describe your observations in great detail, what the dog looks like (expression, body language, does he look to you a 2nd time after you point, a 3rd time before he gets it?) Think up things you want to look for and write them down and go by them systematically.
You could chart it like, dog#1, dog#2, dog#3 (or just use their names) etc and maybe running down alongside the paper, day#1, day#2 etc. On the heading, describe your experiement. In each line put down your observations for each dog, how they reacted in the first minute, what they did in the next minute or whatever you want to set for your scientific critera...how long it took dog#1 to choose the container with the food in it when you pointed with your finger, then when you pointed with your foot maybe, then perhaps see if your gaze alone will cause any of the dogs to choose the right container.
Then you could go onto another page with another heading for another experiement, in how the dogs react to some other human cue, some human body language that dogs don't do perhaps. I don't know. I'm just thinking out loud.
You can do a Google search and look for more to research by writing in what you want to look for, maybe starting out more specifically and then, if needed, broaden your search with less stringent criteria.
Here's a student's paper I saved in "My Favorites" because I enjoy reading stuff like this. Maybe it might give you ideas.