**Welcome Back to Class!**

Iโm thrilled to see you all back and ready to dive into another exciting lesson. Today, we are going to explore further on our previous lesson on **Weight**. Understanding weight is important because it helps us measure and compare objects, and itโs something we use in our daily lives, whether weโre baking a cake, weighing our pets, or figuring out how heavy our school bags are!

### Lessonโs Objective

In todayโs lesson, we will:

- Learn about the metric table of units of weight.
- Understand how to convert between different units of weight.
- Solve mathematical problems involving weight.
- Practice adding, subtracting, and multiplying weights.

**Metric Table of Units of Weight**

Letโs start by looking at the basic units of weight in the metric system. The metric system is a decimal-based system of measurement used all over the world, and itโs very easy to understand once you get the hang of it.

The table below shows the key units of weight in the metric system:

Unit | Abbreviation | Equivalent in Grams |
---|---|---|

Milligram | mg | 1/1000 of a gram |

Gram | g | 1 gram |

Kilogram | kg | 1000 grams |

**Fun Fact**

A milligram is so light that itโs like a tiny speck of dust, and a kilogram is about the weight of a large book!

**Conversion of Units of Weight**

To measure different weights accurately, we often need to convert between units. Here are some important conversions to remember:

- 1000 milligrams (mg) = 1 gram (g)
- 1000 grams (g) = 1 kilogram (kg)

Letโs break down what these conversions mean. If you have something that weighs 1000 milligrams, itโs the same as saying it weighs 1 gram. Similarly, if you have 1000 grams, thatโs equal to 1 kilogram.

**Example**: Imagine you have a packet of sugar that weighs 2000 grams. To find out how many kilograms it is, you divide by 1000:

$$ 2000 \, \text{g} \div 1000 = 2 \, \text{kg} $$

**Mathematical Problems Involving Weight in Open Sentences**

Now, letโs apply what weโve learned by solving some mathematical problems involving weight. An open sentence is like a math problem with a blank that we need to fill in.

**Example 1**: *If a bag of rice weighs 5000 grams, how many kilograms is that?*

To solve this, we divide by 1000:

[ 5000 \, \text{g} \div 1000 = 5 \, \text{kg} ]

**Example 2**: *A small bag of flour weighs 250 grams. How many milligrams is this?*

To solve this, we multiply by 1000:

[ 250 \, \text{g} \times 1000 = 250,000 \, \text{mg} ]

**Addition and Subtraction of Weight**

Adding and subtracting weights is just like adding and subtracting any other numbers, but itโs important to make sure the units are the same.

**Example 3**: *If you have 3 kilograms of potatoes and you buy 2 more kilograms, how many kilograms do you have in total?*

[ 3 \, \text{kg} + 2 \, \text{kg} = 5 \, \text{kg} ]

**Example 4**: *You have a 500 gram bag of nuts, and you eat 150 grams. How much is left?*

[ 500 \, \text{g} โ 150 \, \text{g} = 350 \, \text{g} ]

**Multiplication of Weight by One-Digit and Two-Digit Numbers**

Multiplying weights is also straightforward. Letโs look at some examples:

**Example 5**: *If one apple weighs 150 grams, how much do 6 apples weigh?*

[ 150 \, \text{g} \times 6 = 900 \, \text{g} ]

**Example 6**: *A box of chocolates weighs 250 grams. How much do 12 boxes weigh?*

[ 250 \, \text{g} \times 12 = 3000 \, \text{g} ]

Since 3000 grams is the same as 3 kilograms, the total weight of 12 boxes is 3 kilograms.

**Fun Fact**

The metric system makes it very easy to multiply and divide because itโs based on 10s. This is why converting between units is so simple!

**Letโs Reason**

Think about everyday situations where you use weight. Have you ever tried baking a cake with your parents and had to measure out flour or sugar? Thatโs a practical use of understanding weight. Or maybe youโve weighed your pet at the vetโs office โ knowing how to read and understand those measurements is very important!

### Quiz & Evaluation

Letโs see how much youโve learned, complete this quiz to test your knowledge.

Question 1: How many milligrams are in a gram?

**Conclusion**

Today, weโve learned about the different units of weight in the metric system, how to convert between them, and how to solve mathematical problems involving weight. Weโve practiced adding, subtracting, and multiplying weights, which will help you in many real-life situations.

Remember, understanding weight and measurements is not just about math โ itโs about being able to navigate the world around you more confidently and accurately. If you have any questions or want to learn more, please feel free to ask in the comment section below or explore additional resources on this topic.

I hope you enjoyed our lesson on weight. Keep practicing, and youโll master these concepts in no time, see you in the next lesson!