Building the body of your slide show
Your slide show should tell a story and each slide should contribute something significant. Keep asking, "what does this slide add to the story?" If you can't come up with a suitable answer, then you'll need to either modify or remove your slide.
How much information should go on each slide?
You should try to break your story into smaller pieces and try to put each piece on its own slide. In cases where you have too much information, you should probably break it into multiple slides.
Remember that slides are free. You should use as many as you need to tell the story. Spending too long on a slide will cause your show to drag. That said, you should try to keep the limits of the assignment; you teacher wants to see what can do with a certain number of slides.
Look at Some Sample Slides
Experiment and Be Creative
The good news is that PowerPoint is a remarkably flexible program. If something doesn't seem to be working out, you can change your mind. If you try to be creative and make a show that you think people would learn from and enjoy watching, then you're probably on the right track.
Don't forget to apply what you learned from creating the Puppy slide show.