Air and the respiratory system

Some of you requested for me to put this on my blog:

"The permanent gases in gas we exhale are 4% to 5% by volume more carbon dioxide and 4% to 5% by volume less oxygen than was inhaled."

Source: https://en.wikipedia.org/wiki/Breathing#Composition

You do not have to remember the percentage of each type of air that you breathe in and breathe out.

You need to know that the air we breathe in is composed of mainly nitrogen, followed by oxygen, and lastly small amount of carbon dioxide, water vapour and other gases.

Source: http://www.slideshare.net/stumpy2878/composition-of-air

For Activity 2.1 in your Systems Workbook, we watched this video about breathing into limewater today.

For Activity 2.3 in your Systems Workbook, we are going to make a model to show how our lungs work. Please prepare the following materials:

• a plastic bottle (please ask an adult to cut away the bottom of the bottle)
• 2 balloons
• a straw
• a rubber band
• some plasticine

The following video shows us how the model can be prepared.