I have these four glasses of water and I have some salt, sugar, some flour that is art and some sand with me and what I'll do is I'll try and mix each of these substances with water and I want you to observe what happens. All right so these four have now become mixtures. A mixture has two or more than two substances in it. The first one has salt and water, this one has sugar and water, this one has flour and water and this one has sand and water. So all of these are mixtures but I'm sure you observe some difference among them right. Not every mixture is looking the same. Let's try and look closely. This is a mixture of salt and water. Well are we able to see the salt that we try to mix in it? No right we can't see it, it's completely disappeared. Let's look at the second mixture now that is sugar and water. Well again we can't see sugar right, it's completely dissolved, it's completely mixed with water. There is a little bit of left at the bottom but you can try to mix it some more then gradually it will dissolve completely. So one thing is common in both of these mixtures, salt and water and sugar and water that is we cannot see the salt or sugar that we added to the water and these type of mixtures in which the components are dissolved completely, they are mixed completely they cannot be seen are called homogenous mixtures. Now let's have a look at the other two mixtures. So this is the one with flour and water when we try to mix water with water. Well what do we see here? We can clearly see the flour added right, it has not been mixed, it has not been dissolved. In fact it has settled at the bottom. Okay let's look at the last mixture. Similar thing over here right, the sand has settled at the bottom, sand did not dissolve in water. So these type of mixtures in which the components do not completely mix and the components can be clearly seen. For example we can see the flour and sand clearly in that mixture. These type of mixtures are called heterogeneous mixtures. And there are many more examples of homogenous and heterogeneous mixtures. Why don't you try and identify some of those examples around you?