Capacity

Let's dive into our first worked example on reading capacity.

Let's work through our second example on converting units. Our problem is: A common jerrican, which we see everywhere in Kenya, has 5.75 litres of water. We need to find out how many millilitres that is. We need our key rule. To convert litres to millilitres, what do we do? We multiply by 1000. Let's repeat that: multiply by 1000. We set up our multiplication. We have 5.75 litres times 1000. Let's perform the calculation. When you multiply by 1000, you simply move the decimal point three places to the right. 5.75 becomes 5750. 5.75 times 1000 equals 5750. We write our final answer. The jerrican contains 5750 millilitres of water. Very good. We should always check our work. The best way to check a conversion is to reverse it. If we have 5750 mL, dividing by 1000 should bring us back to 5.75 L. It works perfectly! Always do a quick check like this to be confident.

Solving a real-life example from our own context. Imagine you are a parent preparing for a Sunday party. You have one soda and one juice to mix for punch. This process of combining different amounts of liquid is our topic for this example: Adding Capacities. For the party drinks, we have 1.5 liters of soda and 750 milliliters of juice. Can we add these numbers directly? 1.5 plus 750? We cannot. Why? Because the units are different. Just like you can't directly add Kenyan shillings and US dollars without converting to one currency, we can't add liters and milliliters directly. Step 1 is crucial. Step 1 is to convert everything to milliliters, which is the smaller unit, to make adding easier. Our chart shows the conversion. Remember, 1 liter equals 1000 milliliters. 1 point 5 liters is one and a half liters. That's 1000 mL plus another half, which is 500 mL, giving us 1500 mL. The 750 mL of mango juice, since it's already in milliliters, stays as 750 mL. Step 2 is straightforward. That both amounts are in the same unit, milliliters, we can simply add them. What's 1500 milliliters plus 750 milliliters? (Pause)... That's 2250 milliliters. Write that down clearly. Step 3 is about presenting our final answer in a suitable way. Is 2250 milliliters the best way to say it? Think about it. If someone asked you how much punch you made, would you say 'two thousand two hundred fifty milliliters' or would you say 'two point two five liters'? The second one might be simpler. We can express it either way. Both are correct. 2250 milliliters is the same as 2.25 liters. That's the total mixture. The key lesson here is, before you add capacities, always check the units. Convert them to be the same first, just like we converted everything to milliliters. Then add, and finally, give your answer in a clear, suitable unit. Excellent work, everyone.

Everyone, let's wrap up our session on litres and millilitres with a summary and some real-world applications. First, let's lock in that core rule. One litre is exactly equal to one thousand millilitres. The golden process we learned is this: to compare or add any amounts of liquid, you MUST convert them into the same unit first. How do we use this in real life? First, think about buying cooking oil. You might see a 2-litre bottle and a 500-millilitre bottle. To know which is a better deal, you'd convert them to the same unit to compare the price per litre or millilitre. Secondly, rainwater storage. In many homes, you might collect water in a tank or a jerrican. If you collect 50 litres one day and 12,000 millilitres the next, you need to convert to add them up and know your total water saved. Third, in farming. Mixing solutions for crops is common. The instructions might say to mix 5 litres of water with 250 millilitres of pesticide. Again, convert to the same unit to measure accurately. For your final challenge... I want you to go home and estimate the capacity of a common item, like a kettle, a sufuria, or a drinking glass. Is it 1 litre? 1.5 litres? Maybe 500 millilitres? Think about it. You could compare it to a known 1-litre water bottle. This is how maths becomes a practical skill. You've all done fantastic work today grasping these units of capacity.