Idea One which is the traffic light is a tool for the gym. It has clearly been too long since I have driven and I accidentally drew the stop light at the bottom. Green means go faster to get to your target heart rate, yellow means keep doing what you are doing and red means slow down you are going too fast. There are particular zones listed on gym equipment – going faster builds endurance and not as fast burns fat, etc.
Idea Two would be more for kids, maybe in a science museum. The found heart rate aligns with an animal. Slower heart rates show slower moving animals and faster heart rates show faster moving animals.
Idea Three is a tool for taking your pulse. You press a button to start and then see your heart rate flashing. After 15 seconds passes the first light illuminates, then 30 seconds lights the 2nd, 45 seconds the third, and 60 seconds the fourth. This is a quick and easy way to check your pulse. I imagine that the seconds lights would look like lotto ping pong balls.