c. Convert units such as milliliters to liters or miles to kilometers. [Einheiten umrechnen wie z.B. Milliliter in Liter oder Meilen in Kilometer.]

Nein

Twelve test persons state that they manage to convert units without any problems, five test persons find this task somewhat difficult and three test persons even find it very difficult.

None of the 20 test persons express any difficulties in understanding the term "mile". However, eight test persons (TP 03, 08, 09, 10, 13, 15, 16, 17) do not think of the conversion of miles into kilometers when answering, but of something else:

• "I immediately think of cooking or baking with American recipes, where everything is given in "cups”.” (TP 05)
• "First of all I think of measures of length, cm in dm and m etc." (TP 10)
• "If I measure something in the measuring cup, e.g. half a liter, then that is 50 cl and 500 ml. Or meters in kilometers." (TP 12)
• "Convert one pound of coffee. I prefer grams." (TP 13)

Another ten test persons (TP 01, 05, 06, 07, 11, 12, 14, 18, 19, 20) can understand the term "mile", but they do not know the conversion factor:

• "All those simple units from milli to micro or no idea what, yes, but from miles to kilometers that's something else. I'd have to look up, what is a mile." (TP 01)
• "Well, there are certain difficulties with miles and kilometers, because I would have to look it up first because I don't know. I'd have to know how long a mile is first." (TP 14)
• "I don't know now how to express miles in kilometers." (TP 19)

This leaves two test persons (TP 02, 04) who know the conversion factor from miles to kilometers and take this into account in their answers. Test person 04 explicitly deals with the conversion of both mentioned examples: "Milliliter in liter is a decimal shift and miles in kilometer is 1.6 and this has to be converted.” (TP 04)

Except for test persons 02 and 04 (conversion of miles to kilometers) and 05 (conversion of "cups" to grams), the majority of respondents only consider the conversion of units within the metric system when answering.

When asked how easy or difficult it was for them to answer this statement about the conversion of units, only four test persons (TP 06, 07, 08, 14) classified this as "rather difficult", mainly because they did not know the conversion factor from miles to kilometers.

Only two test persons consider both examples when answering. If the conversion between metric and American systems is of central importance, this should be recorded explicitly and above all individually:
"Convert units of different measurement systems, e.g. miles to kilometers."
[„Einheiten unterschiedlicher Messsysteme umrechnen, z. B. Meilen in Kilometer.“]
If this is not desired or irrelevant in terms of the construct, only examples within a system should be used:
"Convert units such as milliliters into liters or meters into kilometers"
[„Einheiten umrechnen wie z.B. Milliliter in Liter oder Meter in Kilometer.“]

true