 How do you do bonding? It's what I call the stuff of life because without it I wouldn't be here talking to you today. Why do I call it that? Because it's what gives water its amazing properties, all of which is needed for life on Earth. So how can you explain or present this fairly abstract concept to students and in a way through activities that makes it come alive for them, relevant to their lives and exciting. Well there are quite a few activities that I'll present to you today and I hope it will give you some idea. It takes you quite a simple glass, fill it up with water, right to the brim. Let children see that it's really really right to the top. Then the question is how many coins can I put in here before it spills over? They'll predict maybe one, two, three and then you start put it halfway in and then just let it drop so that there's minimal spill. And it's two, three and you just keep going four. And eventually by the time you're getting to nine and ten they're getting really quite intrigued and they start looking carefully at it and if they do they'll see that there's quite a bulgy meniscus becomes apparent and eventually they're on fourteen or fifteen and the first spill happens. Right then the obvious question is well is that applicable to all liquids and we can test that out with paraffin. Another liquid we go through the same activity, fill the glass up with paraffin right to the brim and then we start putting coins into that one and one, two, three and it's already spilling over. So why the difference between paraffin and water? And the reason lies in hydrogen bonds. Between the water molecules they're very strong hydrogen bonds whereas in the non-polar paraffin they're very weak on a vast force. Hydrogen bonds are so strong they're capable of defying the laws of gravity that's what we can see. And quite clearly that surface tension in that meniscus is a very visible sign of the strength of that hydrogen bond. This is where detergents come in. Let's see what happens when we add a single drop of detergent to the meniscus on this glass of water. Wow, the whole thing has collapsed. What's happened to these hydrogen bonds? Somehow those detergent molecules have broken those bonds. How does that work? And for that we really need to have a look at the nature of the detergent molecule. So let me show you. The typical liquid soap molecule is like this. It's got a long carbon chain. That's non-polar. There are 12 carbon atoms in there. And then it's got a polar head. The sodium sulfate when you dissolve it in water that sodium goes off. So essentially it's a non-polar tail with a polar head. Now the meniscus of the water we've just seen you've got your little water molecules held together by hydrogen bonds. Put your detergent molecule into it and what happens is those bonds break and all the polar heads now latch onto the water molecule. End of hydrogen bonds. Okay, then there's another very important element to your teaching is how can you make these concepts come alive for the students? Where are they applied in everyday life? And with this one it's easy because there's quite a number that you can draw on. Honey, for example, it's properties. It's very sticky. Where does that stickiness come from? It's the hydrogen bonding between the sugar molecules. Water forms a lovely round drop. If I take a bit of cooking oil, put it on a plate, drop some water onto it. You'll see the nice round surface. And water just doesn't wet the oil. Why? Because of hydrogen bonding in the water molecules. That makes it difficult for us to wash our dishes because water doesn't wet grease. How do we get that grease off? And that's where detergents come in. And on top of that drop of water we put a drop of detergent and voila. We see the detergent at work. Breaking those hydrogen bonds and enabling the water to get into and wet the oil, grease, dissolve it and so we can wash it. Well, I shared some ideas of teaching with you today and really I invite you to share any ideas you have with me. I will put them up. I'll give you proper acknowledgement for your ideas when I do that. Please send them along to me on this email address.