Thank you very much for your valuable advices. 

I have made an revised version of learning activities as per attached.

The LO is too large to be uploaded, please access through the link below.

https://drive.google.com/file/d/0B83svc1Ax3dxdHBnekNZcUNkYVE/edit?usp=sharing

The design rationale is at

https://drive.google.com/file/d/0B83svc1Ax3dxbDlpelA5RXdqS00/edit?usp=sharing

The learning activities at

https://drive.google.com/file/d/0B83svc1Ax3dxcmk4bTB6NGV1U0U/edit?usp=sharing

 
Ada