Video: Choosing the Suitable Unit to Weigh an Elephant

Which of the following is closest to the weight of an elephant? [A] 8 kg [B] 10 kg [C] 700 kg [D] 30 kg [E] 4 kg

02:22

Video Transcript

Which of the following is closest to the weight of an elephant? Eight kilograms, 10 kilograms, 700 kilograms, 30 kilograms, or four kilograms.

This question is getting us to think about the most suitable measurement for the weight, or the mass, of an elephant. We need to use our understanding about how heavy an elephant might be and also the units of measurement that are shown in the answers. We’re given four possible answers. And the unit of measurement that’s used in all of them is kilograms. Now, there’s really only two things that we can apply here to help us find the answer. Because the question is based on real life, we can use real-life facts to help us. The first real-life fact we can think about is the weight of an elephant. We may not know what the weight of an elephant is, but what can we say about it? What we can say is that an elephant is very heavy. We couldn’t pick one up, for example.

The second real-life fact that we could use to help us is to think about what a kilogram actually is. A kilogram is the same as 1000 grams. To give us an idea of what one kilogram feels like when we hold it, we can think about things we might find in the kitchen. For example, did you know a litre of water weighs about one kilogram. A good one to think about is a bag of sugar. The bags of sugar that we might find in the kitchen cupboard often weigh one kilogram. So we’re looking for one of our answers that’s going to be a large weight. If we go through the measurements in order, we can quickly narrow our answers down.

Four kilograms is about the weight of four bags of sugar. Eight kilograms is about eight bags of sugar. And we can keep visualising bags of sugar to understand that none of these weights are the right weight for an elephant. Even 30 kilograms is too small. We can imagine a lorry delivering some bags of sugar to a supermarket, and there are 30 bags in the box perhaps. Is this the same weight as an elephant? Of course not. The best answer we have is the largest number we have. The closest of these to the weight of an elephant is 700 kilograms.

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