 Welcome back to Kids Fun Science. My name is Ken. Today's experiment is the ineffective drinking straw. As always adult supervision is required. What you need for this experiment is two straws and a glass of water. To start this experiment off I need a glass of water and two straws. I'm using plastic straws so you can see the liquid going up. So attempt. First what we do all the time is we put a straw in water and we attempt to pull water into our mouth but now when we do it a second time we place a second straw that's in our mouth but not in the water and then attempt to drink from that straw and you're gonna see that it's almost nearly impossible. The water will come almost up to your mouth but won't completely get there and you can't really see it because the water is clear. So what I'm gonna do is add a little bit of food coloring in here so you're able to see the liquid going up the straw and then we're gonna do another attempt. First I'm just gonna show you the liquid going up on a single straw and then I'm gonna do the two straws one in the water and one outside the water and I'm going to try to suck up the liquid with both straws and attempt it which will not work. So the science behind this is you don't actually suck liquid through a straw. Air pressure pushes on the surface of the liquid in the glass and forces that liquid up the straw into your mouth. This happens when you reduce the pressure inside the straw by expanding your lungs. If the atmospheric pressure is greater than the surface of the water in the straw then the water will be forced up the straw. In order for this to happen air pressure in your mouth must first be reduced. By letting air into your mouth through the other straw the pressure within your mouth can never be reduced below the atmospheric pressure therefore you cannot drink out of the straw. You might be able to pull some liquid but you're not gonna be able to drink. So go ahead and give this a try at home and let me know what you find out in their comments below. I believe you're not gonna be able to get any liquid into your mouth because you don't actually suck liquid up a straw. Atmospheric pressure pushes that liquid down and up the straw for you. I hope you enjoyed this video. Remember to click thumbs up and to subscribe. Thanks for watching!