Grade 4 Science - End of Semester 1 Review | Baamboozle - Baamboozle

If a material changes from a solid to a liquid, does it become a completely different substance? 如果一种材料从固体变成液体，它会变成一种完全不同的物质吗？

No. A change of state is a physical change, so the substance stays the same. 不会。状态变化是物理变化，所以物质保持不变。

Why can a liquid take the shape of a container while a solid keeps its own shape? 为什么液体可以呈现容器的形状，而固体却保持自己的形状？

Because particles in a liquid can slide and move around, but particles in a solid are locked together. 答案：因为液体中的微粒可以滑动和到处移动，但固体中的微粒是被锁在一起的。

When we hit a drum, why does it make a sound? 当我们敲击鼓面时，为什么会发出声音？

The kinetic energy (movement) from hitting the drum changes into sound energy. 敲击鼓面产生的动能（运动能）转化成了声能。

Why can you smell a cake baking in the kitchen even if you are in the living room? 为什么即使你在客厅，也能闻到厨房里正在烤的蛋糕味？

The particles in a gas (the smell) move very fast and spread out to fill the space. 气体（气味）中的微粒运动非常快，并扩散填充整个空间。

What happens to the energy of a substance when it changes from a liquid to a solid (solidifying)? 当物质从液体变成固体（凝固）时，它的能量发生了什么变化？

The substance loses energy and the particles move slower. 物质失去了能量，微粒运动变慢。

Can energy change from one form to another? Give an example from your house. 能量可以从一种形式转化为另一种形式吗？请举一个家里的例子。

Yes. For example, a lightbulb changes electrical energy into light and heat energy. 可以。例如，灯泡将电能转化为光能和热能。

Is a powder (like salt or flour) a solid or a liquid? Why can it be poured like a liquid? 粉末（如盐或面粉）是固体还是液体？为什么它可以像液体一样倾倒？

Solid. It can be poured because the grains are so tiny, but each individual grain is a solid. 固体。它可以倾倒因为颗粒非常细小，但每个单独的颗粒都是固体。

When iron, water, and air mix together, they make Rust. Is this a physical change or a chemical reaction? Why? 当铁、水和空气混合在一起时，它们会产生铁锈。这是物理变化还是化学反应？为什么？

Chemical reaction. It creates a new substance (rust). 化学反应。因为它产生了一种新物质（铁锈）。

Why can a Gas change its shape and fill a whole room? Describe its particles. 为什么气体可以改变形状并充满整个房间？描述它的粒子。

Particles are far apart and move very fast in all directions. 粒子之间距离很远，并向各个方向快速运动。

Describe how particles are arranged in a Solid. Do they move around? 描述固体中粒子的排列方式。它们会到处移动吗？

Particles are tightly packed together; they only vibrate and do not move around. 粒子紧密地排列在一起；它们只振动，不会到处移动。

All matter is made of tiny pieces. What happens to these pieces when we heat a substance? 所有物质都由微小的碎片组成。当我们加热物质时，这些碎片会发生什么？

They gain energy, move faster, and move further apart. 它们获得能量，运动得更快，并且距离变得更远。

Name two Electrical Appliances you have at home and explain what they do. 列举两个你家里的电器，并解释它们的作用。

Examples: Kettle (heats water), Toaster (toasts bread), Fan (moves air). 例如：电水壶（烧水）、烤面包机（烤面包）、风扇（让空气流动）。

What is the difference between Melting and Solidifying? 熔化和凝固之间有什么区别？

Melting is solid to liquid. Solidifying is liquid to solid. 熔化是固体变成液体。凝固是液体变成固体

What do we call the energy an object has because it is moving? 物体因为运动而具有的能量称为什么？

Kinetic energy. 动能。

If you put a cold spoon into hot tea, the spoon gets hot. Explain why this happens. 如果你把一把冷勺子放进热茶里，勺子会变热。请使用“转移”这个词解释为什么会发生这种情况。

Heat energy transfers from the hot tea to the cold spoon. 热能从热茶转移到冷勺子。

We know energy cannot be destroyed. List two things energy can do. 我们知道能量不能被摧毁。列出能量可以做的两件事。

Energy can transfer (move) and change form. 能量可以转移（移动）和改变形式。

What type of energy is stored in the food we eat? 我们吃的食物中储存着哪种类型的能量？

Chemical energy. 化学能。

In a food chain where a cat eats a mouse, which animal is the Predator and which is the Prey? 在一个猫吃老鼠的食物链中，哪种动物是捕食者，哪种是猎物？

The cat is the predator. The mouse is the prey. 猫是捕食者。老鼠是猎物。

Explain the difference between a Herbivore and a Carnivore. 解释草食动物和肉食动物之间的区别。

A herbivore eats only plants. A carnivore eats only animals. 草食动物只吃植物。肉食动物只吃动物。

Why does every food chain start with a producer? Where does the producer get its energy from? 为什么每个食物链都以生产者开始？生产者从哪里获取能量？

Producers make their own food; they get energy from the Sun. 生产者自己制造食物；它们从太阳获取能量。