Whether you are a Primary 6 student or parent, one of the most challenging topics in the P6 Maths Syllabus is definitely Speed. Although the weightage of the Speed questions in the PSLE Math Paper may not be high, knowing how to solve them can make a significant difference in getting that A*.
Back to Basics – The Speed Formula
Speed questions that appear in Paper 1 are usually foundational in nature. Most of the time, they can be solved as long as you are armed with the Speed Time Distance formula (Also known as Time Speed Distance formula or Distance Speed Time formula).
Essentially, there are 3 components that are involved. Speed is a measure of how fast an object travels from one place to another and is usually expressed in m/s or km/h, Time is the duration of travel and Distance is a measure of how far the object travels.
If a car travels at a speed of 60 km/h and you drive it for 2 hours, it would naturally cover a distance of 60 km/h x 2 h = 120 km. So the relationship between its speed, time and distance is simply Distance = Speed x Time, makes sense?
Speed questions in Paper 1 will usually provide you with 2 variables out of the 3 (speed, time or distance). Your task is then to solve for the missing third value. These questions are fairly straightforward. The answers can be obtained by simply plugging in the known values into the formula and working it out.
Now, what if the Speed question is not as simple as that?
For speed questions that appear in Paper 2, the word problem may involve more complicated events, such as having the 2 objects moving in different directions, traveling some overlapping distance, catching up etc. This is the part where most students get confused.
Is there a way to help you solve such speed questions easily? Thankfully, there is.
In the next section, we’ll take a look at this useful problem-solving technique called the “draw a picture” or “draw a diagram” strategy and how it can help you.
How to solve Speed questions by using “Draw A Diagram” Strategy
When it comes to solving speed questions, using the “Draw a diagram” strategy is highly recommended.
The main challenge that most students face when doing questions on Speed is that they are unable to comprehend the question. This happens because they cannot visualize what is happening. Sometimes, the length of the question is too long for them to “digest” and the fact that too many things are happening doesn’t help either.
Drawing the speed diagram helps you “see” better and gets rid of the confusion. As you are drawing the diagram to represent what is going on in the question, you’ll be forced to identify the key people/objects involved, the locations and their travel paths. This helps you have a better understanding of the relationship between the various entities and picture the sequence of everything.
Moreover, as you are drawing, you are actually describing the solution to the problem. See how taking away the burden of language helps us focus on the Mathematical aspects of the problem?
However, it is important to remember that the drawings are just representations of the problem as you go through the thought processes. Hence, although the drawing needs to represent the problem accurately, it doesn’t have to be perfect.
Check out this video if you want to see this strategy in action!
This video uses an example of a Speed question to show you important problem-solving skills. We will first look at what to look out for when reading the question. Then, we will draw the speed diagram to represent what the word problem is all about. Finally, we will solve it using the basic Speed time distance formula.