1. 
Fill in the blank:

A reasoned guess that can be tested is called a .

2. 
Fill in the blank:

In the scientific method cycle, after making an observation, scientists first ask a .

3. 
What is the first step scientists usually take when investigating a natural phenomenon?

4. 
Why did Lewin's parents allow him to use the sodium sulfite for the experiment?

5. 
Fill in the blank:

The substance found in both the magic marker and the ink remover is called .

6. 
True or False: According to the text, a hypothesis makes it possible to make predictions.

7. 
True or False: In the story, Elsa notices that an ink remover changes the colours of felt-tip pens, just like the magic marker.

8. 
Fill in the blank:

When the results of an experiment do not support the hypothesis, scientists must set up a new .

9. 
What must a lab report (Protokoll) include, according to the text?

10. 
True or False: A solution of sodium sulfite in water, like baking soda and soft soap, is alkaline.

11. 
Which substance was shown to cause the red cabbage juice to change colour?

12. 
Fill in the blank:

Adding pieces of apple while cooking red cabbage turns the liquid .

13. 
Fill in the blank:

Observations recorded during an experiment should not yet contain any .

14. 
Fill in the blank:

The step in which observations are explained and the hypothesis is checked is called the .

15. 
True or False: In the red cabbage experiment, cooking red cabbage in water alone produces a blue-violet colour.