Your StAIR looks great source for students to learn the triangles, especially for 2nd or 3rd graders. The explanation was very clear and easy to understand. When considering its audiences, this instruction would be better to understand to have less words rather than to explain the concepts in full sentence.
Using sliderocket to present your lesson is fabulous with a brief instruction on bottom of presentation. With the icon for next slide other than simply clicking anywhere in slide would suggest more polished look because there is "BACK TO QUIZ' button.