As we continue to learn about the human body, we moved into a lesson on muscles. First, Miss M did an experiment involving a paper arm and yarn muscles. By measuring the muscles, she learned how each half of the pair shortens to bend or straighten the arm.
Next, she opened and closed her fist as many times as she could in 30 seconds. After a quick 10 second rest, she did it again. We discussed how she was able to do it fewer times the second time, because her muscles were tired. Then she tried to see how long she could keep her arms up in the air without support, and we discussed how eventually her arms got so tired that she had to lower them.
We ended by watching the Magic School Bus Flexes its Muscles (we got the video from our library, but I have linked to the episode on You Tube). All in all, a fun lesson on muscles work.