Instructions :

 

   1) Choose two examples per group

 

• (Better either two “small size” or two “big size” examples, so that the difference in scale is not too big !).

 

• Calculate the ratio in size between the bigger and the smaller of your two examples. That is : answer the question “How many times is example A bigger than example B ?”

 

An example could be as follows :

 

a picornavirus (20 nm) and Clostridium tetani (appr 5 µm long)

Ratio = 250

 

 

  2) then look for two everyday life objects, with a similar ratio.

 

For instance :

 

the diameter of a basketball (0,245 m) and the Tower of Hercule (beacon, 55 m)

Ratio = 245

 

below you can find the daily object database :

 

  3) You will then conclude that :

 

"If a the size of a picornavirus was the same as the diameter of a basketball, then the size of Clostridium tetani (a bacterium) would be the same as the one of the Tower of Hercule"

 

 

 

But students can also :

 

 

Perform 2D or 3D models of one example of each organization level (each group of students will be free to choose the organisation levels they want).

 

Examples :

 

• building of a scale model (planets of the solar system for example) ;

 

• building of a wall frieze showing different levels of organisation (Virus, bacterias, human and / or plant cells…) using a relevant scale ;

 

• building of a document (using a relevant ITC tool such as Draw) showing 2 or more examples in a single page taking into account their size difference...