Lesson video

Hi, I'm Miss Kidd-Rossiter and I'm going to be taking today's lesson on Displacement-time graphs.

It's the second lesson of two on this topic, and it's the last lesson in our ratio and rates of change in real life graphs unit.

Before we get started, make sure you're in a nice quiet place, free from all distractions, you've got something to write with and something to write on and a ruler that is also going to be really helpful for today's lesson.

If you need to pause the video now to get any of that sorted, then please do.

But if not, let's get going.

So I'd like you to try this, match the graphs to the maps of the routes taken, assuming that a constant speed is maintained.

So on all the graphs on the Y axis, we've got the distance from home and then on the X axis, we've got the time taken.

We've got three different routes that could have been taken.

So an equilateral triangle, a rectangle and a square.

Your job is to match each route to each graph.

Pause the video now and have a go at this.

Excellent work, here's the answers.

I'm not going to go through these right now because we're going to talk about it in the Connect.

So pause now and check your work.

Excellent, let's move on then.

So we've got Karla here, she's got this root, which is an equilateral triangle.

She's going from home to school, then from school to the shops and then from the shops back home.

And we know that that is represented by this graph.

Let's now look at why.

So I'm going to think about different points on the route from school to the shops and measure how far it would be to home.

So, first of all, we know from home to school is six kilometres.

If we pick another point here, for example, point A, then we can measure how far it is from point A to home.

And that's slightly less than it is from school to home.

So we can also write that, here.

So, on each of these lines, home is at this side and then wherever she is on her route is on the right hand side.

Let's pick another point.

So point B this time, this is slightly shorter, again, slightly closer to home.

So we can represent that here.

So this lines are the same length as these lines.

I've just drawn them horizontal so it's a bit easier for you to see what's happening.

If we keep picking points, we can see that it keeps getting shorter for a while and then something happens.

So let's take another point E, what happens here? That's quite close there, but you can see that this one here for point E is maybe slightly further along than it is for point D.

Let's look at F and see what happens.

This is definitely longer.

G, what happens there? Definitely longer and H, what's happening there? That's interesting.

And then she gets to the shops and we know that the shops are six kilometres from home.

So can you see the shape that these distances make? When we measure along from different points on this route.

Where else can you see that shape? Excellent on that graph.

So we can see that she gets slightly closer to home, and then she gets further away from home and it's not linear.

So well done, if you matched those together.

Anthony, then this time, he's going from home to work, then from what school.

There from school to pick up his sibling, and then he's going from his siblings school back to home.

So first of all, from home to work, we represent it like this is, we're getting further away from home.

Then from work to school, he gets further away from home to nonlinear, right? Then he gets slightly closer to home.

And then finally he goes home from his siblings school.

So that's why this one maps to that.

You're now going to apply your learning to the independent task.

So pause the video here, navigate to the independent task.

When you're ready to go through some answers, resume the video, good luck.

How did you do on that independent task? Let's talk about it together.

So if we look at our axes where we've got time and distance, and remember you also will be drawing with a ruler much nicer than mine.

This is an isosceles triangle where there's two sides of the same length.

So we go up until we meet the furthest point, which would be here.

Then we come back towards home, but not in a linear way this time.

And then once we reach there, which is this point, here we come back to home, excellent.

And then for the pentagon, your graph might have looked something like this.

Excellent, really good work.

Well done.

What are the implications if a constant speed is not maintained? Well, then the graph would look very different, Wouldn't it?.

Now for the explore task, complete the missing graph and shape for the journey sketched.

Assume that a constant speed is maintained.

Pause the video now and have a go at this task.

Excellent, what did you get? What did you think? I'm looking forward to seeing some of your answers.

Remember that this here from our work last lesson means that the distance hasn't changed and this time is going on.

So don't let that put you off, that's it for today's lesson.

So thank you very much for all your hard work.

If you've drawn some lovely displacement-time graphs that you'd like me to see, then please share your work Oak National.

Please ask your parent or carer to share your work on Twitter, tagging @OakNational and #LearnwithOak.

Don't forget to go and take the end of lesson quiz so that you can show me what you've learned and hopefully I'll see you again soon, bye.