The Human Heart
Celebrate Valentine’s Day by learning about real hearts, not just glitter-and-doily ones.
1. A child's heart is roughly the size of his fist
2. The heart circulates the blood supply about 1,000 times each day
3. The heart pumps the equivalent of 5,000 to 6,000 quarts of blood per day
4. If the blood vessels in the body were joined end to end, they would circle the Earth two and a half times
5. Most women's hearts beat faster than men's
6. Scientists have found that laughing is good for your heart
7. Ancient Egyptians believed intelligence stemmed from the heart
8. Blood is almost 80 percent water
9. The heart begins to beat just four weeks after conception
10. You could drive a truck 20 miles using the energy created by the heart in one day
What you need: Balloons, turkey basters (at least one balloon and baster per every two students), water
What to do: Pair children up in groups of two. Give each group a balloon and a turkey baster. Show students how to use the baster to squirt air. Challenge the children to use the basters to blow up the balloons. (One student may need to hold the balloon tight around the baster while the other fills the balloon with air.) Then let the students repeat the experiment with water. Show them how to draw up water with the baster, then inject it into the balloon. When the balloon is full, have them gently compress the balloon to expel the water.
Talk about it: Ask students to show you their muscles. (Expect a lot of arm flexing!) Then have them point to their hearts. (Most students will know that the heart is in the upper-left portion of the chest.) Explain that the heart is a muscle that pumps blood through their bodies. When the heart fills with blood, it expands, like the balloon when it's full of air or water. When the heart contracts, it pumps the blood out to the body-just like a full water balloon expels water when compressed.
Feel the Beat
What you need: Timer or watch with a second hand
What to do: Have the students place two fingers between their jaw and earlobe, then run them down the groove in their neck until they feel a slight pulsation; tell them that pushing feeling is their pulse. Set the timer for 15 seconds and have the students count their pulse; let them call out their answers when the timer beeps. Multiply the most common answer by four. This is the students' resting pulse. Then have the students run or jump in place for one minute before taking a second 15-second pulse rate. Multiply by four to calculate the students' exercise heart rate.
Talk about it: Each heartbeat sends a wave of blood through the body, which can be felt as the pulse. Each pulse signifies one heartbeat. Different people have different pulse rates, although a normal resting heart rate for a child is 70-120 beats per minute. (Average heart rates slow with age. An adult's resting heart rate is usually 60-80 beats per minute.) When people exercise, their hearts beat faster to supply the muscles of the body with more oxygen. Muscles need oxygen to work effectively; each heartbeat pumps fresh oxygen to the muscles. The harder a body works, the quicker the heart beats.
What you need: Empty cardboard tubes (one for each student)
What to do: Pair students and have them take turns listening to each other's hearts with the cardboard tubes. (Show students how to place one end of the tube against their ear; the other end should rest against the upper-left portion of their partner's chest.)
Talk about it: Ask students to describe what they hear. Heart sounds-traditionally described as "lub-dub"-are the heart at work. The "lub" and "dub" are the blood flowing through the heart.
What you need: Empty 20-ounce plastic soda bottles (one for each student), scissors, vinyl tubing (allow 60 cm per student), masking or duct tape
What to do: Using a craft knife, make a small starter slit in each bottle, about halfway between the top and the bottom. Have students cut around the bottle, starting at the slit. Discard the lower portions. Students should place the vinyl tubing into the mouth of the top portion; secure with tape. Encourage them to listen to their hearts by placing the tube near their ears and the funnel-shaped portion on their chests.
Talk about it: Most students will be familiar with stethoscopes. Explain that doctors and nurses use stethoscopes to check the heart's health. Stethoscopes concentrate the sounds of the heart and deliver them directly to the ear so that doctors and nurses can hear the heart more clearly.
What you need: Toy trucks, cardboard, blocks
What to do: Label the upper-left portion of the cardboard "right atrium"; the lower-left portion of the cardboard is "right ventricle." Draw a road connecting the right atrium and right ventricle, then draw a road from the right ventricle across and off the cardboard on a diagonal. (This road will represent the pulmonary artery. Label it "to the lungs.") Label the upper-right portion of the cardboard "left atrium" and the lower right "left ventricle." Draw a road to connect the atrium and ventricle and another road on a diagonal from left ventricle across and off the cardboard. (This road will represent the aorta. Label it "to the body.") Have students load a truck with a block and drive it from the right atrium to the right ventricle and off the cardboard to the lungs. Unload the block at the lungs, then load in a second block. Drive the truck from the left atrium to the left ventricle and to the body.
Talk about it: The heart has four chambers: right atrium, right ventricle, left atrium, left ventricle. "Old" blood-blood low in oxygen-enters the heart through the right atrium and flows to the right ventricle. The right ventricle pumps the blood to the lungs, where it picks up oxygen. The oxygen-rich blood flows into the left atrium, then to the left ventricle. The left ventricle then pumps it to the rest of the body. Encourage students to run the truck along the proper route-right atrium, right ventricle, lungs, left atrium, left ventricle, body-to establish a basic understanding of the circulatory system.
Find a "Healthy Hearts" learning activity for grades 1-3 here.