1. Depth-Time Graphs – Demonstration
This resource provides animated demonstrations of the mathematical method.
Check animations and delete slides not needed for your class.

2. Depth-Time Graphs
Jack needs to fill his two fish tanks.
The large fish tank is the same height and width, but twice the length.
Which tank will fill first? How much quicker?
The two taps give the same rate of water.

3. Jack needs to fill his two fish tanks.
Depth-Time Graphs
Jack needs to fill his two fish tanks.
The large fish tank is the same height and width, but twice the length.
Which tank will fill first? How much quicker?
Small
Big
MAX
Depth
Time

4. Jack needs to fill his two fish tanks.
Depth-Time Graphs
Jack needs to fill his two fish tanks.
The large fish tank is the same height and width, but twice the length.
Which tank will fill first? How much quicker?
The volume increases at the same rate,
but the depth increases at a faster rate in the small tank.
The speed of increase is represented by the gradient.
Small
Big
MAX
Depth
Time

5. Amanda also has two tanks.
Depth-Time Graphs
Amanda also has two tanks.
They are the same height, but the large tank is twice the volume.
On the same grid, sketch the depth-time graph for each container.
MAX
Small
Big
Depth
Time

6. Faster rate of depth increase
Depth-Time Graphs
What does the depth-time graph look like if
the tanks were on top of each other?
The total container is double the height
MAX
Faster rate of depth increase
Depth
Slower rate of depth increase
Time

7. During each section the rate is constant.
Depth-Time Graphs
This tank is made from three sections of equal height.
Sketch the depth-time graph for the container.
Fastest
Depth
Medium
Slowest
Time
During each section the rate is constant.

8. Depth increases at fastest rate.
Depth-Time Graphs
This tank fills faster at the top than at the bottom.
Sketch the depth-time graph for this container.
Depth increases at fastest rate.
It is not a constant rate at any time.
Depth
The gradient is always increasing.
Starts slow
Time

9. Increasing at a steady rate
Depth-Time Graphs
This tank is made from a sphere and a cylinder.
Sketch the depth-time graph for the container.
Increasing at a steady rate
Rate of increase speeds up
Depth
Starts fast, then rate of increase slows
Time

10. Match each container with a depth-time graph.1 A B C 2 G D E F 3 4 5 6 7

11. Answers 1 E A B C 2 G D E B F 3 4 5 6 7 G F D A C

12. Sketch a depth-time graph for each container.B C G D E F

13. Answers A A B C G B D E F C D E F G

14. tom@goteachmaths.co.uk Questions? Comments? Suggestions?
…or have you found a mistake!?
Any feedback would be appreciated .
Please feel free to