Lesson video

This is unit one, computing systems and networks communication.

It is less than two of six, Selecting Search Results.

For this lesson, you will need an awareness of the worldwide web and how it works.

If you're going to be using an internet connected device to access the websites, please, make sure that you do so with supervision from a parent or guardian.

Hello everyone, My name is Jane Adamson, and I'm your computing teacher.

I'm looking forward to teaching your lesson.

To prepare, you will need something to write with, something to write on, and an internet connected device.

Please take a moment before you start to clear away any distractions, including turning off any notifications on apps, so you can focus.

Try to find a quiet space where you can work without disruption during the lesson.

Pause the video at any point when you need to.

Okay, let's make a start with lesson two, Selecting Search Results.

In this lesson, you describe how search engines select results, explain why we need tools to find things online, recognise the role of web crawlers in creating an index, and relate search term to the search engines index.

The key vocabulary that you will be covering is index, web crawler, bots, and search engine.

A brief history of the world wide web.

In 1989, Tim Berners-Lee invented the world wide web, to make it easier to share documents with other scientists.

The worldwide web or the web, is an information system where documents and other web resources are identified by URLs, which is unique resource locator.

These are interlinked by hypertext and they're all accessible over the internet.

In 1991, the first website was launched.

1994, the first widely used search engine Yahoo! was launched.

In 1998, Google was founded.

Growth of the worldwide web.

Here you can see a table that gives the year with a number of websites starting with 1991.

On the 6th of August, 1991, the first website was launched, so there was only one.

In 1994, when Yahoo! launched, there were 2,738 websites.

Then, in 1998, when Google was launched, there were 2,410,067.

A recent count in 2020, showed that there are 1.

7 billion.

Between 1991 and current day, you can see that there has been a huge growth in the number of websites.

What does this huge growth of the websites mean for finding things on the internet? Pause the video and have a little think about this question, and then press play again when you're ready.

This huge growth in numbers of websites means that it becomes more and more difficult to find information on the internet.

Search engines were developed in order to make it easier to find information on the world wide web.

We are going to learn more about how search engines work during this lesson.

One of the key things, the search engine needs is an index.

Before you find out about indexing on the internet, let's look at a real life example using a book.

You have a book with an index at the back.

You would like to find out more on a certain topic, but what could you do? What does the book have that can help you find things? You can use the index, which is typically at the back of the book.

For example, if you had a book on Greece and you wanted to know more about Athens, you would look for the search term, Athens under A, in the index.

This would give you a page reference.

Then you would go to the page that it suggests in the book and find out more information about Athens.

If you have a book with an index handy, try using the index to find some information in your book.

Pause the video if you need to, and then press play once you've tried it out.

Let's have a look at task one, indexing.

Here you are going to compare searching for something using a book and searching for something using the internet.

Complete the table in your worksheet for task one.

In the second column, write the steps you would go through in the correct order to search for a keyword in a book using an index.

In the third column, write the steps you would go through to search for a keyword using the internet.

You should be doing this from your own memory.

Pause the video and resume, once you have completed the task.

How did you get on? Let's go through the steps for searching using a book.

So, first of all, identify your key words.

Look for the key words in the index, go to the pages for the key word and then check which page is the most useful for your keyword.

For searching using the internet, you would identify your keywords, choose your search engine, enter the keywords in the search box and then click on the web link for one of the results.

So hopefully your table looks something like this.

Take a moment to review your answers with the answers in this table.

You are now going to find out how search engines find things on the worldwide web.

Search engines use bots, which are programmes that run automatically, known as crawlers or web crawlers, sometimes spiders or spider bots.

The bots crawl websites for searchable content, for example, text images and links.

They take a copy of the webpages that they visit and they build up an index, which is stored on the search engine servers in huge data centres, all over the world.

The benefit of indexing.

Let's go back to our scenario, using a book.

By using the index of a book, we found the information more quickly and save time.

This works exactly the same for search engines.

This means that when you type a search in your search engine, the results appear quickly by using the index.

Crawling the web for Athens.

The index is used to respond to searches.

The search word is Athens.

Following the arrow to the search results, you can see that one of the top results is Wikipedia.

Clicking on the blue active link takes you to the Wikipedia entry for Athens, look carefully at the highlighted text, and you can see the amount of searches that the search engine came up with, 243 million.

And beside it, the time it took not 0.

69 seconds.

The speed of the result is because of the efficient indexing used by the search engine.

Task two, indexing the kitchen.

This is an unplugged activity.

You are going to assume the role of a crawler to index things in your kitchen.

Choose five items that you can find in your kitchen.

Look at the table.

One of the items that has been chosen is cutlery.

In the second column, it lists the locations where you can find those things in the kitchen.

For the cutlery, it can be found in the dishwasher or the sink, in the drawer, or on the table.

You might have some more places where your cutlery is.

To complete the worksheet, you must choose five more items that you find in your kitchen, and then act as a web crawler.

Find out the location or locations of where you can find those things in your kitchen.

Complete the second column of your sheet.

Pause the video while you complete task two, restart once you are ready to continue.

Indexing the kitchen.

Indexing the kitchen, task two.

Let's go through some possible answers.

The second item is tea towels and the location where there could be found are on the radiators, in the drawers and on the tea towel rail.

Crockery can be found in the dishwasher, in the sink, in the cupboard or on a table.

Food can be found in the cupboard, on a plate, or hob, in the oven, or in the refrigerator, or even in the freezer.

Sauces can be found in the refrigerator, on the table, or cupboard, and pots and pans can be found in the oven, on the hob, in the sink, or in a cupboard.

It's great if you've got similar answers to these, of course, you might have slightly different things in your kitchen.

Now I would like you to test your index.

How does it work? Is it effective? Compare yours to the one that we see here.

Indexing makes things easier and quicker to find, but does an index help find something that hasn't been indexed? For example, my car keys, or the light switch in the kitchen.

The index doesn't help if the item hasn't been indexed, but that doesn't mean that the item doesn't exist.

How many results? Most search engines will tell you how many results there are after your search term.

So you can see in the Google search, the word is dog.

The search shows just over 6 billion results, and the results appeared and 0.

7 seconds.

Why does some search terms return more results than others? Well, this depends on how often the search term appears in the search engine's index.

Narrowing a search.

There are research terms, dog, black dog, and black Labrador.

What do you think will happen when we type each of the words into a search engine.

The words are more specific and this should result in a smaller number of results.

Task three, narrowing a search.

Take out your internet enabled devices and pause the lesson.

Try entering these different search terms. For the search term dog, as you can see here, this resulted in 3.

2 million search results.

Using your internet enabled device, complete the table.

Resume the lesson once you're finished.

Task three, narrowing a search.

What results did you come up with? You can see from the results in the table that when the search words are more specific, there are less search results.

The index is more effective at coming up with a result that you are requesting.

Keywords or search words are very important.

They guide the search engine to quickly produce a more accurate set of results.

Task four, how does the search engine select results? Write three sentences to explain how a search engine selects results.

Try to include these words, web crawler, webpages, and index.

Pause the video and resume once you've completed the task.

Task four, how does a search engine select results? This is a model answer.

A search engine uses the web crawler, this creates an index of webpages, using an index makes it quicker and easier to bring up relevant results.

How did you do? Did you have something written down like this? It would be great if you could share your work.

Take a photograph or a screengrab, ask a parent or guardian permission, and maybe perhaps share it on Instagram, Facebook or Twitter.

Make sure you tag it with @OakNational and #LearnWithOak.

Well done and good job.