Make Fishing Rods with Magnets
Take the quiz and check your answers!
Click here to take the quiz!Separating Mixtures
, like soda, seawater, and air, which are made of two or more pure substances mixed together. We often separate substances from mixtures depending on what we need. For example, to get salt from seawater, people gather seawater in salt pans and let the ② evaporate using sunlight and wind, leaving the salt behind. This is how sea salt is made.In 2007, a big oil spill happened near Taean, in South Korea, when a ship carrying crude oil crashed into another ship. The oil spilled out into the sea. Since oil is a type of liquid fat, it does not mix with seawater. Instead, it floats on the surface and blocks oxygen from reaching the water. Without oxygen, sea animals and plants can die. The bigger problem is that seawater moves with ocean currents, so the oil keeps spreading. To stop it from spreading, people used oil booms (floating barriers) and placed absorbent pads on the surface of the water to soak up the oil.
When making beef bone soup, there is usually a lot of oil at first, and it needs to be removed. If the soup is hot, the oil mixes with the liquid, so it’s hard to take it out. But when the soup cools down, the oil turns into a white solid and floats on top. This makes it easier to remove the oil. You can remove the floating solid ③ by scooping it out with a spoon or a strainer.When cultivating rice, you must first choose the best seeds, which are full and firm inside. Saltwater is used for this process. When the rice seeds are placed in the saltwater, the good, heavy seeds ④ to the bottom, while the hollow ones ⑤ to the surface.You throw away the floating seeds and plant only the ones that sink. Sometimes, gold is mixed with sand in nature. This is called ⑥ .
To collect the gold, put the sand into a shallow pan, add water, and gently shake it. The heavier gold sinks to the bottom, and the lighter sand stays on top. After repeating this several times, only the gold remains. This shows that we can separate the materials we need from a mixture by using their different properties.
Getting salt from salt pans
Photo courtesy: KOREA.NET at www.flickr.com
Oil boom to stop the spread of crude oil
Click here to take the quiz!How to Separate Various Mixtures
Finding the Common Features of Methods for Separate Mixtures
| (a) Sifting Sand at a Construction Site | (b) Sifting Flour for Baking | (c) Catching Only Large Fish |
|---|---|---|
| To use fine sand at a construction site, a sieve is used to separate out gravel and large pieces of sand. | When making bread or cookies, flour is sifted to remove lumps and make it soft and fine. | To protect sea life, fishing nets with tiny holes are not allowed. This helps catch only big fish and lets baby fish go free. |
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| ㉠ 공사장에서 모래 고르기 |
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| 공사장에서 고운 모래를 사용하기 위 해서 체를 이용하여 자갈이나 굵은 모 래를 골라내요. |
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| ㉡ 고운 밀가루 체 치기 |
| 빵이나 쿠키를 만들 때 고운 밀가루를 사용하기 위해서 밀가루를 체로 쳐요 |
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| ㉢ 큰 물고기만 잡기 |
| 바다 생태계를 보호하기 위해서 망이 너무 촘촘한 그물은 사용이 금지되어 있어요. 큰 물고기만 잡고 새끼 물고기 는 잡지 못하도록 한 조치이지요. |
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in materials.How to Separate Mixtures
Today, Kongji, who is being scolded by her stepmother, needs to separate the beans, rice, and millet that are mixed together in a basket. What tools could help her?
Separating a Mixture of Salt, Sand, and Iron Filings
There is a mixture of salt, sand, and iron filings. We will use tools to separate each material. Write the tools used for the separation.
Mixture of salt, sand, and iron filings
Use a ⑨ to remove the iron filings.
Mixture of salt and sand filings
Mix the rest with water, then use a ⑩ to separate the sand. The sand will stay on the filter paper.
It stays on the filter paper.
It is divided into sand and salt.
Iron filings
Use an ⑪ to evaporate the water and get the salt.
Click here to take the quiz!Making a Magnetic Fishing Toy
Activity 1
Please follow the instructions and assemble the educational kit in the order specified.
Activity 2: Magnet-Based Sorting Machine
There are aluminum and iron cans. To recycle them properly, they need to be sorted by type. When cans are placed into a sorting machine with a magnet, those that are attracted to the magnet will stick to the magnetic moving plate and be collected in Box (A). The cans that are not attracted will continue along the conveyor belt and be collected in Box (B).
Identify which cans are collected in Box (A) and Box (B) based on the sorting machine.
Box (A): Cans made of : ⑫ , Box (B): Cans made of : ⑬ .
Activity 3: Infer Like a Scientist
Food News: Metal Powder Found in Chili Powder
Metal powder has been found in some chili powder sold at supermarkets and markets, shocking consumers. Experts explain that this happens because the metal parts inside the grinder rub against each other and wear down during the chili grinding process. Chili powder is commonly used in Korean cuisine, so many people are worried about the safety of the food they eat.