See your blood:
Find places that you can see your own blood. Use some tools to help you find it: flashlight, mirror.
Wrist, under tongue, eyeballs the blood is easily visible. Shine a flashlight through closed fingers to see blood colour.
Blood is always red (not blue). When it is oxygenated it is bright red, and when it is depleted of oxygen it is darker red. Some veins look blueish green because of how light interacts with the skin over the veins.
Blood is red because iron (which carries the oxygen within the haemoglobin molecules in our red blood cells) turns red when it combines with oxygen (just like rusted iron is red because it is oxygenated). Some animals (lobsters, spiders and snails) have blue blood because they use copper instead of iron to carry oxygen, and copper is green-blue when oxygenated.
Find your pulse::
The blood moves through the blood vessels to bring oxygen to all parts of your body.
You can feel the blood moving in some places on your body - called a pulse. It is easier to feel where an artery presses against a bone.
Find your pulse in your wrist: gently press the first two fingers of one hand on the wrist below the thumb of the other hand - this is the pulse in the radial artery, called the radial pulse.
Find your pulse in your neck: place the first two fingers on the side of the neck under the jaw bone - this is the carotid pulse. (This is one of the strongest pulses as it is close to the heart. The carotid artery supplies blood to the brain. Only do one side at a time, so there is no danger of cutting off blood supply to the brain.)
Other pulses (see https://www.youtube.com/watch?v=qhgAEfLh1Ck to find them): temporal pulse (on the temples at the side of the head) and proximal brachial pulse (between the large muscles on the upper inner arm). Harder to find are behind the knee (popliteal artery), near the ankle joint (posterior tibial artery), and on the top of the foot (dorsalis pedis artery).
If you can cross your arms to feel the pulse in your wrist and neck simultaneously (set up one, then find the other), you may notice that the wrist pulse is just behind the neck pulse - you are feeling the wave of blood pressure moving away from your heart to the outer parts of your body.
Measure your heart rate:
Each pulse is a push of blood from the heart. The heart beats your whole life.
Count how many pulses in 15 secs. (about 16, so 64 beats a minute, so about 30 thousand in a year, so 3 billion in a lifetime).
Try measuring your heart rate before exercise, and after. Try different kinds of exercise (jumping rope, lifting a two-pound weight, hula-hooping, walking) and measure heart rate immediately after. Your pulse will slow again after only 15 seconds.
Listen to your heartbeat:
Your heart makes a noise. Listen to your neighbour’s heart or use a stethoscope to hear your own.
The heart beat sound is from the rush of fluid behind closing valves: "Lub" is the AV valves (between atria and ventricles) closing and the rush of liquid behind them. "Dub" is the semilunar valves (between ventricle and artery) closing and the rush of liquid behind them.