Transcript

JANET SUMNER

Now it's time to do your first practical science experiment. You don't need much equipment. You need a microwave or a conventional oven, a set of scales, a potato, and a piece of graph paper printed off from your study journal.

It's a very simple experiment. We're basically going to bake a potato to destruction. But it's all about understanding how to set up, observe, and record in a scientific manner. So the first thing is I'm going to weigh my potato and note down the start weight in grams. It's 103 grams.

And now I'm going to stick it in the microwave. Right, in it goes. And I'm going to set the timer for one minute. Now, you can do this in a conventional oven, but obviously it's going to take a lot longer, and you'll probably need to do the measurements every 10 or 15 minutes or so.

[DING]

Right, time's up, so I'm going to take it out and weigh it again, usual health and safety with hot objects. OK, so let's see. And the weight's gone down to 98 grams. So I'll record that. After one minute, 98 grams.

Now I'll pop it back in and give it another minute.

[DING]

That's another minute up, so I'll do another measurement. It now weighs, oh, 84 grams. I'm just going to give it one more minute and see if the weight continues to fall.

[DING]

Weight 74 grams. Now, you're probably going to have to do this seven or eight more times to get an original data set. But what we need to think about next is how you're going to present this data in a way that's meaningful.

One of the most visual ways to do this is with a graph, which is where this comes in. So we have two variables that we're measuring, the weight of the potato in grams, which is changing over the amount of time in minutes that it spends in the microwave or the oven. And I can use this graph paper to show those two variables.

This is the vertical axis, which I'm going to mark weight in grams, and then the horizontal axis, which is going to be my time in minutes. Now I have to decide what scale to put on these axes. So the start weight of my potato was 103 grams. So if I start from naught and mark off every centimetre as 10 grams, then I should have enough space to fit in my weight measurements.

So that's 10, 20, 30, 40, 50, 60, 80, 90, 100, and 110 grams. And then for the time, I probably don't want to microwave a potato of this size any longer than 10 minutes. So I'll make 10 minutes my maximum, and every centimetre on my horizontal axis I'll mark out as a minute.

One, two, three, four, five, six, seven, eight, nine, 10. Now I can start plotting my data and see if a trend emerges. So the start weight at zero minutes was 103 grams about there. Then after one minute, it's gone down to 98. So I move along the horizontal axis to one minute, and then I go up to 98 grams.

Then two minutes, I'm at 84, so up from two minutes to 84. And then finally at three minutes, we're down to 74, which is about there. And I can join up my data points, and you can see I've got a trend starting to emerge.

So what we'd like you to do is finish the experiment. I'm going to do another four or five measurements and plot them. Don't forget to give your graph a title, Potato Experiment, and note whether it was done in the microwave or the oven.

You've done the observation and the recording of the data. Now it's time to do the interpretation of the data by joining in the discussion.