In A Heartbeat

 This is the month for my annual realization that RED is not my favorite color and I really do not like pink very much either. All of this I rediscover as I pass by those glowing, glistening, sparkling RED classroom decorations made by so many loving hands to celebrate Valentines Day. So, I try to bypass the color by concentrating on a symbol of the holiday - THE HEART. At some time near the fourteenth of February we do an experiment which demonstrates our pulse and shows that we each really do have a beating heart.

Demonstration

 Gather together enough miniature marshmallows to have one for each student and one for yourself. Make narrow four-inch "sticks" by slicing plastic straws lengthwise, making one "stick " for each marshmallow. Insert this stick in the marshmallow. (Alternatives for the candy and straw equipment could be a ball of dough and a toothpick - just so long as the combination stays lightweight.) Each student must carefully observe the demonstration. Lay your left hand, palm up and still, on the table. Find your wrist pulse. Stand the marshmallow on top of the pulse point and carefully watch the tip of the straw. Sure enough you will see the straw twitch with each pulse and the number of twitches you count in fifteen seconds multiplied by four will be in the 65 -75 range - normal for adult humans.

Experiment

 Set the children up in twos or threes so that one can perform the experiment while the other watches and counts, and then they change places. They will find that a child's heart rate is considerably faster than that of an adult.

Observations

 During a recent kindergarten discussion of this experiment the question of heart rates in other animals came up. What kind of a heart rate does Lauren's pet rabbit, Peter (depicted here with his friends), have? How about my dog, Tweed, who lies sleeping so quietly I think her pulse must come close to stopping? It was time to check with my veterinary friend.She took Tweed's pulse by touching the femoral artery inside her right hind leg (not a spot where we could easily balance a marshmallow!) and found it was 110, typical for a dog. My friend also gave me the following heart rate values which I took back to the children. They found the comparison between their favorite animals and themselves VERY INTERESTING. Clapping hands at the rate of an elephant or a lion's heartbeat is fairly achievable, that for a giraffe or a goat's is still possible, but that busy hamster's heart outpaces us.

Heartbeats per Minute

Bat750  Camel30
Cat120  Chick380