Luyện nói tiếng Anh bằng Shadowing qua video: Chemical and Physical Changes – Quiz Edition
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Music Take notes as you watch this video and take the short quiz at the end.
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Every day we observe a myriad of changes around us.
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A car can get crushed into a compact cube of metal at a junkyard.
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A fire can burn logs in a fireplace, turning them into ash and smoke.
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Bread bakes to a crispy golden brown loaf.
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And metal rusts when exposed to moisture and air.
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Each transformation, whether big or small, is a testament to the ever-changing nature of matter around us.
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In science, we dissect these transformations and categorize them into two primary types, physical and chemical changes.
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In a physical change, the form or state of matter changes, but the molecular structure remains the same.
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No new matter is made.
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For instance, consider the process of ice melting.
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As the temperature rises, the ice transforms from a solid state into liquid water.
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Even though the state and appearance change, the water molecules are still H2O, maintaining their original molecular structure.
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This transformation illustrates a physical change, where the state alters without changing the substance itself.
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Let's take a look at some examples of physical changes in action.
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Consider a sheet of paper.
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With a pair of scissors, the paper is cut into smaller pieces.
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The shape and size of the paper change, but chemically, it is still paper.
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Each piece retains the same properties as the original sheet.
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Another example of a physical change.
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Now think about a piece of modelling clay.
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In your hands, it can be moulded, stretched and shaped into various forms, a ball, a cube, or even a miniature animal.
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Though the shape transforms, the composition of the modelling clay remains consistent.
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The changes are physical, not chemical.
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Consider the act of making a salad.
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Crisp lettuce is torn, vegetables are sliced, and ingredients are mixed together in a bowl.
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The various components change in shape and texture as they are prepared and combined, but their chemical composition remains the same.
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The lettuce is still lettuce.
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The tomato remains a tomato.
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The salad, brimming with an assortment of colours and textures, exemplifies a physical change.
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Lastly, visualize a glass falling to the floor and smashing into pieces.
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The integrity of the glass is compromised.
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It shatters.
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However, each fragment, sharp and irregular, is still glass.
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The chemical composition hasn't altered.
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Thus, we are once again witnessing a physical change.
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Chemical changes involve a transformation at the molecular level, where the original substance turns into a different substance with new properties.
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It is characterised by the formation of new chemical substances and often involves energy changes,
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evident through the release or absorption of heat, light or sound.
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Various indicators like change in colour, production of gas or the formation of precipitate can denote a chemical change.
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When iron is exposed to oxygen and moisture, it undergoes a chemical change resulting in in the formation of a new substance, rust, iron oxide.
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This is evident by the change in color from metallic gray to brownish red, and the alteration in the material's properties like strength and appearance.
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The chemical composition of iron changes, proving that it's not just a physical alteration, but a chemical change.
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In a fireplace, wood burns and transforms into ash, heat and gases.
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This is accompanied by the release of light and heat, indicating a chemical change.
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The original wooden logs, primarily composed of cellulose and other organic compounds,
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are converted into new substances like carbon dioxide, water vapour and ash.
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The visible flames and the change in material composition underscore this transformation as a chemical change.
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When the raw ingredients like flour, eggs and sugar are baked, they transform into a cake.
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It's not just a state change.
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New compounds are formed during the baking process, changing the taste, texture and colour.
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The cake's aroma and the solidified fluffy texture are evidence of a chemical change where new substances with distinct properties are created.
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Plants convert carbon dioxide and water into glucose and oxygen using sunlight.
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This transformation is marked by the emergence of new substances, glucose and oxygen, which were not originally present.
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The absorption of light energy and the creation of food and oxygen signify a chemical change.
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When baking soda and vinegar are mixed, there is an immediate fizzing and bubbling reaction.
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This is due to the formation of carbon dioxide gas, a new substance.
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The chemical reaction occurs as acetic acid in the vinegar reacts with the bicarbonate in the baking soda to form carbonic acid,
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which quickly decomposes into water and carbon dioxide gas.
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The evolution of gas, change in temperature, and the formation of new substances like carbon dioxide,
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water and a type of salt are clear indicators of a chemical change.
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Do you think you can identify changes to matter as either physical changes or chemical changes?
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Let's put your knowledge to the test.
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Thank you.
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I'm
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going to
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go ahead and put it in the middle of the room.
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I'm
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going to go to the next video.
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Let's go.
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I'm
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going to
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go to the next video.
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I'm
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going to
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go ahead and put it in the middle of the room.
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Thanks for learning, and I'll see you next time.
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Don't forget to subscribe!
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Từ vựng và ghi chú luyện nói cho bài học này
Bài luyện nói trình độ B2 này dựa trên video “Chemical and Physical Changes – Quiz Edition”. Những từ được nhắc lại nhiều nhất trong bài: chemical, substance, physical, transformation, dioxide. Video này có 78 câu và 879 từ để luyện shadowing. Phần lời nói dài 10:30. Người nói nói chậm, khoảng 84 từ mỗi phút, đủ thời gian để bạn bắt chước từng âm. Chỉ 73% số từ nằm trong 3.000 từ tiếng Anh thông dụng nhất, nên từ vựng khá khó.
Từ vựng quan trọng trong video
15 từ khó nhất trong video, kèm phiên âm và nghĩa:
| Từ | Phiên âm | Nghĩa |
|---|---|---|
| bake động từ | /beɪk/ | nướng |
| lettuce danh từ | /ˈlɛt.ɪs/ | rau diếp |
| fireplace danh từ | /ˈfaɪɹpleɪs/ | lò sưởi |
| vinegar danh từ | /ˈvɪnəɡɚ/ | giấm |
| rust danh từ | /ɹʌst/ | rỉ sét |
| ingredient danh từ | /ɪnˈɡɹiːdi.ənt/ | thành phần |
| glucose danh từ | /ˈɡluː.kəʊz/ | glucozơ, glu-cô |
| cube danh từ | /kjub/ | hình lập phương |
| tomato danh từ | /təˈmeɪ.toʊ/ | cà chua |
| moisture danh từ | /ˈmɔɪs.t͡ʃɚ/ | độ ẩm, khí ẩm |
| convert động từ | /kənˈvɝt/ | cải đạo |
| compound danh từ | /ˈkɑmpaʊnd/ | hợp chất |
| acetic tính từ | /əˈsiːtɪk/ | axetic |
| compose động từ | /kəmˈpəʊz/ | phổ, sáng tác |
| myriad danh từ | /ˈmɪɹi.æd/ | vạn, muôn |
Phát âm cần chú ý
Người nói dùng 7 dạng rút gọn, ví dụ I'm, don't, hasn't. Hãy nói theo dạng ngắn đúng như bạn nghe.
- Âm “sh” và “zh”: alteration /ɔl.tɚˈeɪ.ʃən/, absorption /æbˈsɔɹp.ʃn̩/, brownish /ˈbɹaʊnɪʃ/, shatter /ˈʃætɚ/, visualize /ˈvɪʒuəˌlaɪz/
- Từ dài — đặt trọng âm cho đúng: molecular /məˈlɛk.jə.ləɹ/, alteration /ɔl.tɚˈeɪ.ʃən/, ingredient /ɪnˈɡɹiːdi.ənt/, indicator /ˈɪn.dɪˌkeɪ.tə(ɹ)/, bicarbonate /baɪˈkɑɹ.bə.neɪt/
Những âm người Việt thường gặp khó:
- Cụm phụ âm cuối — đọc đủ từng âm, đừng nuốt âm cuối: transform /tɹænsˈfɔɹm/, rust /ɹʌst/, ingredient /ɪnˈɡɹiːdi.ənt/, evident /ˈɛv.ə.dənt/, compound /ˈkɑmpaʊnd/
- Âm /tʃ/, /dʒ/ và /ʒ/ — tiếng Việt không có, đừng đọc thành “ch” hay “gi”: texture /ˈtɛkst͡ʃə(ɹ)/, moisture /ˈmɔɪs.t͡ʃɚ/, junkyard /ˈd͡ʒʌŋkˌjɑɹd/, visualize /ˈvɪʒuəˌlaɪz/, miniature /ˈmɪn.(i)ə.tʃəɹ/
- Âm /æ/ — mở miệng rộng hơn âm “e”: transform /tɹænsˈfɔɹm/, absorption /æbˈsɔɹp.ʃn̩/, salad /ˈsæl.əd/, categorize /ˈkætɪɡəˌɹaɪz/, myriad /ˈmɪɹi.æd/
Cách luyện với video này
- Nghe hết video một lần, chưa cần nói, và ghi lại những từ bạn chưa biết.
- Nói đuổi từng câu ở tốc độ bình thường, lặp lại mỗi câu đến khi nhịp của bạn khớp với người nói.
- Ghi âm giọng mình rồi so với bản gốc, chú ý các từ như bake, lettuce, fireplace.
Phương Pháp Shadowing Là Gì?
Shadowing là kỹ thuật học ngôn ngữ có cơ sở khoa học, ban đầu được phát triển cho chương trình đào tạo phiên dịch viên chuyên nghiệp và được phổ biến rộng rãi bởi nhà đa ngôn ngữ học Dr. Alexander Arguelles. Nguyên lý cốt lõi đơn giản nhưng cực kỳ hiệu quả: bạn nghe tiếng Anh của người bản xứ và lặp lại to ngay lập tức — như một "cái bóng" (shadow) đuổi theo người nói với độ trễ chỉ 1–2 giây. Khác với luyện ngữ pháp hay học từ vựng bị động, Shadowing buộc não bộ và cơ miệng phải đồng thời xử lý và tái tạo ngôn ngữ thực tế. Các nghiên cứu khoa học xác nhận phương pháp này cải thiện đáng kể phát âm, ngữ điệu, nhịp điệu, nối âm, kỹ năng nghe và độ lưu loát khi nói — đặc biệt hiệu quả cho người luyện IELTS Speaking và muốn giao tiếp tiếng Anh tự nhiên như người bản ngữ.