Video: Tightening the web

﻿Okay, in this lesson, you'll use search terms effectively. We'll explain how the choice of search terms affects the information that you find and we will create some hyperlinks to help us navigate through some webpages. Okay, so before we start looking at search engines and search terms, let's look at this activity about categorising animals. So animals are grouped into different classes based on shared characteristics. What differences can you see between these groups? Have a look and see how many you can see between the different groups here of fish, mammals, amphibians, birds, reptiles, and arthropods. Pause the video for a second and when you're ready, you can resume. Okay, so there are clearly lots of differences between these groups of animals. If we asked a question, for instance, that said, which animals have feathers? The answer would obviously be bird or birds. And if you asked which animals can live in water, well for this one, we'd get overlapping groups. So we could have fish, amphibians, or mammals too. So narrowing results, if we want to return fewer results, then we can put a little bit more detail into our search. So if we're asking a question, because that's effectively what we do with a search engine, we ask it a question, and it will try and answer that question with results of webpages that it's found. So if we look at this question, how can you add to the question down below so only amphibians and mammals is the answer, okay? So which animals can live in water, something can live on land. So you've got to think of a word that you could put in that dotted area that would result in the answer to that question being only amphibians and mammals. I'll give you a second to have a think and then I'll give you the answer. That's right, it would be and. So which animals can live in water and can live on land. So the answer to that one would be amphibians and mammals. Okay, let's take a look at another one and we're going to see how we can combine some groups now. So what word could you add to have the answer as both mammals and arthropods for the following question? So which animals drink milks as, drinks, oh, easy, which animals drink milk as babies, something have more than four legs. So what word could you put in the dotted area there to make sure that the answer was both mammals and arthropods as the answer. That's right, it would be or. So which animals drink milk as babies, or have more than four legs, then you would get the answer of mammals and arthropods. What if you want to exclude some groups or eliminate some results that are not relevant to our search? We can do that as well, by adding a specific operator in there. So what word could you add to the question below to only get arthropods as the answer? So which animals do something, have fewer than five legs. What word would you put in that dotted area? I'll give you a second and then I'll give you that answer again. That's right, it would be not, so which animals do not have fewer than five legs. So all animals that have more than five legs would be arthropods. And lastly, we can combine these, we can kind of join them together to really, really give ourselves a refined search. So for instance, if you ask which animals have wings and are not cold blooded, what would the answer be? That's right, it'll be arthropods again. Okay. So we've used the and operator and we've used the not operator in our question to form a question to really narrow down the result that we would get. Don't forget from the previous lesson that web search crawlers can catalogue huge numbers of pages every single day. And there are lots and lots of pages, potentially billions, that could be returned depending on the keyword that was punched in there in the first place. In the same way that we narrowed down the results of the answers for the categorising the animals, we can do the same thing with a search engine. So when you type keywords into a search engine, it's default operator is and, so if you typed in, in this example, for instance, Edinburgh castle, it would automatically think you want all the webpages with Edinburgh and castle in them, whether or not you do or not. It will add that and in for you. You can see this search here is recorded, has returned 64 and a half million results just by having Edinburgh and castle. So search engines provide the use of these operators to control our searches a little bit more effectively. If we put in the term Edinburgh or castle, well that is going to return any page it finds with the word Edinburgh in or the word castle, and not necessarily both. obviously that's going to have drastic results because there'd be lots of pages with the word or in them, and it would return them. And as you can see, you know, we've gone up from 65 million results to 1.16 billion. So, you know, using the terms wisely or not, you can get more or less results. The not operator, we don't put the word not in, we just use the minus symbol. So if we put in Edinburgh and then not castle using the minus symbol, then that would find pages with the word Edinburgh in, but it would remove all the pages that also have the word castle in as well. So that's really refined that down to 179 million results from the 1.16 billion. And then if you want to really, really focus your search, you can put in what's called a phrase search, so you can put quotes around your search. So what we would do here, we'd put quotes around Edinburgh castle, and that has returned 4.2 million results and it's only returning webpages that've got that specific phrase in the webpages, Edinburgh castle with castle following the word Edinburgh exactly as it is there. Okay, so it's your chance to control a web search. You're going to investigate the impact that these operators have on the number of results returned by a search engine. So you have a worksheet for this task. It's task one, you can pause the video and complete the task. Okay, so how did you get along with that task? Well, for part one, you had to find webpages about Alan Turing or Charles Babbage. Didn't necessarily have to have both in there, you just had to find some information about those two computer scientists. They don't necessarily need to be on the same page, but you would be able to return some results, some 319,000 when I did this one with Turing or Babbage, okay? So it doesn't necessarily mean that they both have to be on the same page, but all will return pages where either Turing or Babbage is found. Okay, so for this one, you were looking for green shade netting, something for the garden, for example, and you could use only two of the words that you were given out of the three or four, green, garden, shade, netting. And the best thing to do here would be to put it in quotes, because if you put green shade in quotes, then you're not going to get results just relating to the shade of the colour green, because the words wouldn't be in that order. And then if you look somewhere close to the top of putting green shade in quotes, in a web search, you'll find websites about green shade netting, so that was the best use of controlling a search for that one. And then lastly, we were looking for restaurants called the Taj Mahal in the USA, but not in New York. So if you remember from when we did the examples, if we want to eliminate something, then we use the not symbol, which is a minus symbol. So we've got Taj Mahal restaurant USA, which was fairly specific, and then we've done a minus and put New York in the phrase in the quotation marks so that we're not just getting, we're not taking pages away that have got the word new and York in them, which was what would be, what would be the default. So that would return 1.58 million results, so we've got a not and a phrase. So well done if you managed to do those properly. Okay, so we've seen before, when we did our previous example, we've only really looked at standalone single webpages. But we know from browsing the web that web pages contain links to many other web pages and I'm sure you've clicked on a webpage or a menu on a drop down and gone somewhere else and read another article that's led to somewhere else. Quite often, many times you'd be looking at something and think, how did I get here? Because you've gone through that trail of those links leading from one to the other. And we can see here how you could browse between pages using these hyperlinks. So if you clicked on the image of the raspberry Pi 4 there, it would take to the raspberry Pi page. And if we clicked on the word blog, it would take us to the blog. And again, you've got this trail of links that you can click on. So web links in HTML, we use the tags to be able to create these hyperlinks. So previously you've put an image in your web pages and you've put some text in there and now we're going to look at putting some HTML hyperlinks in there. So we can see for this image, we've got a link. So we've got an a href to the page that it's going to, and this is an Rpi4 HTML page. And it's saying that the image source, it tells you what the picture's called. So it turning that picture into a clickable link. And then similarly down the bottom, we've got the words find out more, and that is linked to the same webpage, but this time, instead of having an image to click on, we've got the words find out more. Okay, so let's take a look at how we create hyperlinks in our web pages. Okay, so you may remember last time when we were demonstrating how to create a basic page and put an image into a page. Well, what we're going to do now is we're going to look at this page and we're going to edit it slightly so that we can have, we can have this image as a clickable hyperlink, and we can have some text that is also a hyperlink. So this is the text for this page right now. You can see we've got our heading, what we had and we've got our picture and it's linked to that style sheet that we already made down here last time. Okay, so what I'm going to do now is I'm going to add a hyperlink below the image. so just to make sure it goes below I'm going to put it in a new paragraph. And to add a hyperlink, we use an a href, and this is going to be the web page that we want to visit if we click this link. So I'm going to put in www dot snail world dot com, okay? So that's the web address that I would like to be able to go to when my link is clicked. What I put after it here, where the cursor is flashing here is I put what text I want to actually be displayed that's clickable. So I'm going to put here all about snails and I'm going to close my a href tag, and I'm also going to close my paragraph and that's going over on another line now, so... There you go, you can see it all on one line. So what I've done is I've added this line here, okay? So there's a new paragraph, which is this part, and that's closed over here. We have the a href tag equals, and then in quotes, we've got the full URL of where we'd like to visit. We close that here, and then in between here we put what we'd actually like to click on. So if I save this now and I refresh my page, you can see we've now got this clickable link. The mouse changes as you move over and at the bottom you can see where it's going to go. Snail world dot com, which is what we typed in here. And we can check if that works by clicking it. Hey, great, that works. Okay, facts about snails. So what we can also do is we can continue to edit this page. And with this link here, this link, this image, instead of having all about snails, I can copy this. I can copy all of this here. Just going to copy the whole line, I'm going to paste it here. So that effectively will be, I've got two copies of this line here, but instead of it saying all about snails, I'm going to put in all of this, I'm going to take that out, I'm going to pop that there. So now, instead of having all about snails just in text form, I've now got another link which will go to the same website, but instead of it saying all about snails, I'm saying actually, I'm going to make this image clickable too. So if I save that and go back to here, I now get, my mouse changes when I move my mouse over this, that's going to take me to the website, and this was going to take me to the website. We can check it works too. There you go, that works great. So that is how to add hyperlinks to your webpages. Okay, so I hope you enjoyed that demonstration on creating hyperlinks in HTML, and I hope you find it useful and you understood it. You're now going to use your webpage from lesson four and we're going to create a second webpage now, and this one's going to be summarising how to use the different search operators, okay? So you'll summarise how to use or, how to use not, and how to use the phrase operator using quotation marks. You're going to create a hyperlink on both of your web pages so they go back to each other and you can see the format of how you would do that below. So you would use the a href tag. We put the name of the webpage in it, so the file name of the webpage, and then we'd put the text that we'd like to display. So that's the text that effectively will be able to be clicked upon to navigate to that particular webpage. Pause the video here and complete task two. Okay, so let's see if you can remember the impact of different search operators on the number of search results. Okay, so 21,800,000 results for Suez canal, if I use the operator or in between those two words, what number of results do you think I will get? Do you think it will be higher than 21.8 million or lower than 21.8 million? That's right, it would be higher because we're using the word or so it's going to return any page that's got either the word Suez or the word canal in there. So that would be much, much higher. And you can see here, it's over 1 billion results. If I put the word Suez canal, and I put that in quotes, that phrase in quotes, do you think it will be higher or lower than the 1 billion? Yeah, of course it will be lower because we're putting it in a phrase and it's only going to return pages that have got that exact phrase in there. Let's modify it again, we've got the word Suez or canal and then taken away any pages that have got the word canal. Seems a bit weird, doesn't it? So what will that be? Will that be higher or lower? Well, yeah, it's going to be higher because that's going to return 41.3 million results. Effectively, what we're doing here, it says can you explain why? You might even have to think about it for a little second. Suez or canal, well if we just have that, we know from previously that that's going to return a lot of webpages. You know, that's going to return all the ones with the word Suez and all the ones with the word canal in them. And I know I said, and there, but you know, not in the key term sense, but you know, when we're looking at an or keyword, that's effectively what it's doing. It's going to give us all those pages with that in and it's going to give us ones with that in as well, but they don't necessarily have to be in the same page. But here, now we're taking the word canal out of it, so really what we're doing there is we're just looking for pages that have got the word Suez in them. So that's why we're getting 41.3 million. I hope you enjoyed today's lesson and hope you created a really good webpage. You love to share your work on Oak National, I'd love to see it. If you'd like to, please ask a parent or carer to share your work on Instagram, Facebook, or Twitter, tagging @Oak National and hashtag learn with Oak. I'll see you next time.

Worksheet: Tightening the web

Exit Quiz: Tightening the web

Completed: Tightening the web

Search engines index a huge number of web pages against an equally large number of possible search terms. Therefore, finding useful information can be quite tricky. If you understand how to carefully control what you search for, you are more likely to  find what you want, instead of browsing the other millions of web pages you could look at.

Computing

Tightening the web

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