annual project - grade 6

video link

https://www.youtube.com/watch?v=nZrZh_NLuxA&feature=youtu.be

6H Memorable Science Time

Changes in materials

How do things change?
There's two type of changes. Reversible and non-reversible.

What is a reversible change?

Reversible change is changes in materials that can be changed back into their original form.
Examples of reversible change is an ice cube. When an ice cube melts, it becomes a water. Then, a water that is freez is form into an ice cube again.
 http://www.youtube.com/watch?v=MsNfDKkU9ZM

What is a non-reversible change?

Non-reversible change is changes in materials which cannot turn back to their original form.
Examples of non-reversible change is burning a paper. When a paper is burned, it form an ash and the ash cannot change back to a paper or their origanal form.
http://www.youtube.com/watch?v=c-pK6ltdEps

Factors that cause rotting of wood

The rotting of wood is a non-reversible change. It takes place when there is a wood rot fungi and moisture.
When wood is exposed to moisture in the air, it becomes moist. Moist wood is home tobwood rot fungi.
Wood rot fungi attack wood cells which cause the wood become porous and crubbly. Wood rot fungi and moisture cause the wood of the fence to rot and turn black.

Factors that cause rusting

Rust is a layer of reddish-brown substance that is formed on metals such as iron and steel. Rusting is the formation of rust on metals.
The rusting of materials is a non-reversible change. It takes place when there is oxygen and moisture.
When a metal is exposed to the air, it combines with oxygen and moisture. As a result, rust slowly form.
Oxygen and moisture in the air cause rust to form on the metals railings.

Experiment on the science lab.
-Heating a white sugar. After a few minutes, it melts and the colour becomes brown and hard. This is a physical/reversible change.

-Heating a butter does not change it's colour. It just melts. This is also a reversible change.

-Heating a candlewax doesn't form a new material. When it melts, the colour becomes transparent and after a few minutes, it changes to the orginal materials again. This is a reversible change.
-Mixing a flour with water. When this materials mixed, they become a liquid. It does not form a new materials or can be called as reversible change.
-Mixing baking soda with vinegar. When they are mixed, it becomes a liquid and there is puffing bubble above the liquid. This called as a chemical or non-reversible change.

Cells Division

How do cells grow and multiply?

Multicellular organism 

When we grow up, our body increase in size. This because the number of cells in our body is increase.

Cells multiply themselves.The nucleus and cytoplasm of one cell divide to produce 2 cells.The new cells produces are identical to the original cell.

The process can be repeated.The two new cells can latter divide to form 4 cells.

The cells in our body do not live forever.Our skin cells, can live up to 3 weeks, while cells lining our intestines are replace by new cells every 3 days.

Unicellular organism

Unicellular organism also multiply by dividing themselves.Since each unicellular organism is made up of 1 cell. a new organism is produces when cell divide.

Bacteria and paramecia

Unicellular organisms, such as backteria and paramecia, multiply by dividing themselves.

Yeast

Yeast multiplies by a special method of cell division called budding. During the process of budding, a small bud grows from a yeast cell. The bud then increase in size and breaks away from the original  yeast cell.

The experiment

Last time, we did an experiment about yeast.

For flask A its a mixture between yeast and hot water only, while flask B its a mixture of sugar,yeast and hot water.

Flask B is growing better. 

How can we know?

we know from the size of balloon that is increasing.

The sugar help much more for yeast to grow.

This is the picture of the experiment we did last time:

you can see how the yeast grow by budding in this link;

http://www.youtube.com/watch?v=BTHYaf-EuYs

Soil erosion

1.What is soil erosion?
Soil erosion is the removal of soil cause by the wind and rain

2.What are the causes of soil erosion?
The cause of soil erosion is when the soil gets blown by the wind or washed by the rain.

3.What are the effects of soil erosion?
The effects of soil erosion has a negative effects to the environment.It's so dangerous and it might kill so many people.




4.How can we prevent soil erosion?
We can prevent soil erosion by not cutting trees,plant more plants and build retaining walls to hold back slopes of hills and mountains.


5.Reflection
Don't brake the plants like stepping on the grass because plants may die.