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Python lists, and the index that starts at 0
Play Python Lists and Indexes
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How to play Python Lists and Indexes
- Read the first step: a list is a row of boxes, each with an index.
- Move the sliders and switches to change the diagram and watch what happens. The readout under the picture shows the numbers.
- Answer each question. If you are wrong you get a hint and can try again, with no penalty.
- Some steps ask you to make something happen, such as hitting a target value. Experiment until it works.
- Finish the lesson to earn XP and see how many questions you got right first time.
Tips and strategy
- Do not rush. The controls are there to be played with, so try extreme values as well as sensible ones.
- Say what you notice out loud or write it down before you press Continue.
- Use the hint when you are stuck, and then try to explain the answer in your own words.
- Count from 0, and remember the last index is one less than the length.
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FAQ
Python Lists and Indexes: questions
Why does a Python list start at index 0?
Python counts how far an item is from the start, so the first item is 0 steps away. Most programming languages do the same.
What does a negative index do?
It counts from the end of the list: -1 is the last item, -2 is the one before it.
What causes an IndexError?
Asking for an index outside the list, such as index 5 in a list of 5 items (valid indexes are 0 to 4).
What age is this lesson for?
It suits ages 10 to 16 as a first step in Python.
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