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Activity

Balancing and centre of mass in your body

Summary: 
Try balancing activites to find out how your muscles work to keep your body in balance.
Science content (2016 curriculum): 
Biology: Features, Adaptations of Living Things (K, 1, 3, 7)
Biology: Sensing, Organ Systems (4, 5, 6)
Lessons activity is in: 
Materials: 
  • your body
  • a wall
Procedure: 

Try two activities, to experience how your muscles help you keep balance.

1. Stand with your legs apart, your feet spaced at least as wide as your shoulders.
Try to lift and hold your right foot off the ground without moving your upper body - you'll need to put your foot down again quickly as you start to fall.
Now lift your right foot off the ground while allowing your upper body to move, so you can keep balance one one foot. Notice how you changed your body position so that your upper body is over your left foot. Your left leg muscles worked together to shift the weight of your body over your left leg. And now that you are standing on one foot, the muscles in your left leg are constantly adjusting to help keep your balance.
For younger students, it might be best to start with them standing against a wall to prevent them from moving their upper body: Put your left shoulder and foot against a wall. Try and lift up the right foot. It is impossible because you can't shift your weight to balance because the wall is in the way.

Dancers and gymnasts have strong leg muscles because they use them constantly to balance in many different positions. To be able to hold a pose, the dancer's/gymnast's centre of gravity must be directly above the area of contact with the floor.

2. Put your back and heels against a wall. Try and touch your toes without moving your feet.
Now try the same movement without the wall.
A wall makes it very hard to stay balanced while bending down. Without the wall, our muscles work to shift our body dramatically to keep our weight centered over our feet, so that we can stay balanced. We are often not aware of these constant adjustments our muscles are making to keep us balanced.

During sports our body moves a lot. As we kick, hit or move an object, many forces act on our bodies. Our muscles are constantly working to counteract these forces and keep us balanced.

Teaching site: 
Prototyped only (not yet tested in a classroom)