Take a look at the following pictures. What kind of mixture can you make from these ingredients?

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1 reflect Do you enjoy eating corn? What about peas or carrots? Do you enjoy these vegetables by themselves or do you like them mixed together? If you enjoy corn, peas, and carrots on their own, you probably find a mixture of these vegetables even tastier! What other mixtures can you make? What is a mixture? Mixtures are very common. When you combine, or add together two or more different types of things, you make a mixture. The parts that are combined are often called ingredients. Mixtures always have at least two ingredients. They can have many more. The two ingredients in mud are dirt and water. There are many ingredients in a cake. Most cakes include flour, sugar, baking powder, eggs, water, and oil. what do you think? Take a look at the following pictures. What kind of mixture can you make from these ingredients? Sometimes it is easy to see the parts of a mixture. A fruit salad is a mixture of different fruits. You can see the ingredients because they are big. What ingredients can you find in this fruit salad mixture? 15

2 Other mixtures are made of very small parts. The parts might be so small that you don t even see them as separate pieces! Sand is a good example. You might think sand has only one ingredient : the sand. If you look closely, you will see sand has many small ingredients. It has bits of shells, rocks, and other materials. Some mixtures have parts that are so small you can t see them, even if you look closely. The ingredients in these mixtures might be too small to see with your eyes. The ingredients might also be mixed together so well that you can t see them. For example, water and salt combine to form saltwater. You can see water, and you can see salt before it is mixed in. However, once you mix the two you can t see the separate ingredients. Even if you looked very closely, it would still be difficult. Sand is a mixture of many tiny ingredients. What happens to different materials when they are mixed together? Ingredients in mixtures do not change their properties. Suppose you have a pile of red buttons and a pile of blue buttons. You mix them altogether. Do you think you will see a new pile of purple buttons? No, that is not what happens. The red buttons stay red, and the blue ones stay blue. The parts of a mixture keep their properties. Another example is trail mix. It is a mixture of nuts, raisins, and chocolate pieces. What are the properties of nuts? They are crunchy, salty, and brown. What are the properties of raisins? They are squishy, purple, and sweet. What are the properties of chocolate pieces? They are colorful, hard, and sugary. When you add them together to make trail mix, the ingredients stay the same. The nuts still taste salty. The raisins still feel squishy. The chocolate pieces are still colorful. The combination of different tastes and textures is what makes trail mix so delicious! Even when ingredients are difficult to see, their properties are still there. For example, what happens when you mix salt into water? The salt in the saltwater still tastes salty. The water in the saltwater remains clear and wet. Just like with the buttons and the trail mix, the parts of the mixture keep their properties. 16

3 try now Take a few minutes to identify mixtures and their ingredients. 1. Collect 3 5 different types of breakfast cereal. 2. Pour a small pile of each cereal onto separate plates. 3. Identify which cereals are mixtures and which are not. How can you tell which are mixtures? 4. Choose one of the cereals that is a mixture. What are the different ingredients in the mixture? 5. Separate one piece of each type of ingredient. Spend some time observing the ingredients. 6. What are the properties of each ingredient in this mixture? Does the ingredient keep its properties when it is in the mixture? How did you use its properties to separate it? Did you look at its color to separate it? Did you look at its shape? How can the materials in a mixture be separated? Sometimes mixtures need to be separated into their parts. You can use the properties of the ingredients to do this. To separate the parts of trail mix, you can look at the different shapes and colors of the ingredients. Different ingredients also feel differently. You can use your fingers to separate the nuts from the raisins and chocolate pieces. Because the pieces are large and have such different properties, it is fairly easy to separate them. A worker separates small pieces of wheat from big pieces using a sieve. For other mixtures, separating the ingredients is more difficult. Gravel is a mixture of sand and small rocks. How would you separate the parts of gravel? It would be very difficult to pick out every bit of sand with your fingers. One solution is to use a sieve (pronounced siv ). Sieves are tools used to separate small pieces of a mixture from large pieces. A sieve has a section with small holes in it. Gravel is placed in the sieve and shaken. The sand passes through the small holes while the larger rocks that can t fit through the holes remain in the sieve. The mixture is separated into its ingredients after passing through the sieve. Mixtures containing certain metals can be separated with a magnet. Suppose you have a mixture of metal paperclips and plastic paperclips. You can use a magnet to separate the parts. The metal paperclips will be attracted to the magnet. The plastic ones won t be. Holding the magnet above the mixture will pull out all the metal paperclips. The mixture is separated into its ingredients. 17

4 look out Why must sailors bring their own water when they travel on the seas? They are surrounded by water. However, none of this water is drinkable. Humans must have freshwater, not saltwater, to live. Saltwater actually causes more harm than good. The salt dries out your body, leaving you even thirstier. To safely drink seawater, you must first separate the salt from the water. You cannot pick out the salt or the water, however. Instead, you must boil the saltwater. The water boils out as water vapor, and the salt is left behind. You can collect and water vapor: the gas form of water cool the water vapor so it becomes a liquid again! The liquid water is fresh and safe to drink! Looking to the Future: Separating a Mixed Bag of Recycling As we use up Earth s natural materials, it becomes more important to recycle. Today, many families choose to recycle. Some places have laws that require recycling. But how do we separate the mixtures of metal, paper, and glass at the recycling center? At a recycling center, rotating machines first separate out paper and cardboard. Then a huge magnet pulls out the metal materials such as aluminum cans. Finally, giant air blowers blow out the plastics from other items. In three simple steps, the machines separate huge mixtures of recyclables. What Do You Know? Mixtures are very common in our lives. By combining different ingredients, we can make many interesting mixtures. Look at the pictures of various mixtures shown below. 1. Write down the ingredients you see in each mixture. 2. Then, decide how best to separate each mixture into its parts. Circle fingers, sieve, or magnet. Salad: 1. Ingredients: 2. I would separate this mixture using: my fingers a sieve a magnet 18

5 Silverware: 1. Ingredients: 2. I would separate this mixture using: my fingers a sieve a magnet Mixed Grains: 1. Ingredients: 2. I would separate this mixture using: my fingers a sieve a magnet 19

6 connecting with your child Mixing It Up at Home To help your child learn more about mixtures, take a tour around your home so your child may identify and observe mixtures from their everyday lives. Examples include laundry, bowls of fruit, toolboxes, art supplies, piles of leaves, toy boxes, and pen/pencil containers. Encourage your child to identify the different ingredients that make up each mixture and, where possible, to separate them into their parts. Have your child explain how the ingredients retain their properties and how these properties can be used to separate them. If available, have your child use a sieve to separate mixtures of small parts such as a collection of beads, birdseed, or soil; your child can also use a sieve to separate water from pasta or washed fruit. Encourage them to observe the sieve s hole size, and connect that to its ability to separate mixtures. Next, help your child learn more about mixtures by making their own. Many mixtures are made in baking. For example, have your child collect the ingredients needed to bake cookies (flour, sugar, chocolate chips, etc.). Try to focus on the dry ingredients so it is easier for your child to see the separate parts; then, help them to mix all the ingredients together. Here are some questions to discuss with your child: What is a mixture made up of? How many ingredients are there in a mixture? Do the ingredients change their properties when they are added to the mixture? What are different ways to separate a mixture? 20