Grade 8 Science Finals Review

A collection of flashcards covering five core units of Grade 8 Science: Mix and Flow of Matter, Cells and Systems, Light and Optics, Mechanical Systems, and Fresh/Saltwater Systems, explained in simple terms.

What is viscosity?

Is how 'thick' or 'stiff' a liquid is. For example, honey has high viscosity because it is very thick, while water has low viscosity because it is runny.

What is density?

describes how 'crowded' the tiny particles are inside a space. If things are packed very tightly, the object is more dense.

What is buoyancy?

is an upward push from a liquid or gas that helps things float, like an invisible hand holding a boat up.

What is a cell?

is the tiny building block of all living things. Think of them like the tiny bricks used to build your whole body.

What does the nucleus do in a cell?

is like the 'brain' or the 'boss' of the cell that gives all the instructions to the other parts.

What is an organ?

is a group of different tissues working together to do a big job in your body, like your heart pumping blood or your lungs breathing air.

What is reflection?

is when light hits a surface and bounces back, just like a ball bouncing off a wall. This is how mirrors work.

What is refraction?

is when light 'bends' as it moves from one thing to another, like from air into water. It can make a straw in a glass of water look broken.

What is a lens?

A lens is a curved piece of clear material (like glass) that bends light to help us see things clearly, like the lenses in glasses or cameras.

What is a simple machine?

A simple machine is a tool with few or no moving parts that makes work easier, like a ramp (inclined plane) or a see-saw (lever).

What is 'work' in science?

when you use a push or a pull (force) to move something a certain distance. If it doesn't move, no scientific work was done!

What is a hydraulic system?

is a machine that uses liquids under pressure to move heavy objects, like the brakes on a car.

What is the water cycle?

is the way water travels in a big circle from the ground, up into the clouds (evaporation), and back down again as rain or snow.

What is salinity?

a word used to describe how much salt is dissolved in water. Ocean water has high salinity, but lake water usually has low salinity.

Where is most of Earth's water found?

found in the oceans, while only a tiny bit is fresh water we can drink.