Teaching Materials
What is new in this level?
Level 3 adds lists and randomness. This is the first level where running the same program twice can give a different result, which surprises students who assume a program is a fixed recipe. It is a good moment to have them run their code several times before deciding whether it works.
New in this level:
- Making a list with
isand picking from it withat random - Adding an item to a list with
add to - Taking an item out of a list with
remove from
- Slides Present the level, one concept at a time
- Workbook Exercises to print, away from the screen Work in progress
Common mistakes
Students try to print whole lists
A list can't be printed. You can only print one item from the list with at random.
groceries is apples, milk, chocolate print groceries
To print a list of all the groceries, you simply need to put them after a print command. Else you can use the list to print one item with at random.
print apples, milk, chocolate # or groceries is apples, milk, chocolate print groceries at random
Students use the name of a variable or list as regular text
This problem probably occurred in level 2 as well. Now it can happen with lists too.
name is Hedy print Hi my name is name # or animal is rhino, bee, swan print The best animal is... animal at random
Don't use the names of variables or lists in regular text to print. In level 4 this problem is solved with quotation marks.
name is Hedy print Hi I'm name # or animals is rhino, bee, swan print The best animal is... animals at random
Students forget at in at random
Like in the example
birds is sparrow, seagull, robin print birds random
This problem is solved by adding the word at.
birds is sparrow, seagull, robin print birds at random
Students forget to use the print command when also using the at random command
Or they will sometimes put at random at the beginning of the line.
fruit is apple, cherry, banana fruit at random
Emphasize to your students that you always need a print to print text.
fruit is apple, cherry, banana print fruit at random
Students forget to use commas in their lists
In a list items are separated with a comma.
pizzas is funghi tonno quattro stagioni print pizzas at random
After each item on your list, there should be a comma
pizzas is funghi, tonno, quattro stagioni print pizzas at random
Students try to use at random without a list
For example
clubs is Manchester United print clubs at random
Hedy can't print anything at random, because there is no list to choose from.
clubs is Manchester United, FC Bayern Munich, FC Barcelona print clubs at random
Students try to use add/remove without a list
In the example below 'names' is not a list, but a variable. You cannot add anything to it.
names is Jake your_name is ask Who are you? add your_name to names print names at random
There has to be a list first, so you have to add a second name to turn names into a list, for example Amy. If you don't want amy on your list, you can use remove to remove it after.
names is Jake, Amy your_name is ask Who are you? add your_name to names print names at random
Students forget to use to/from in add/remove
Without to/from the add/remove command won't work.
adventures is story, parrot, dice choice is Which adventure do you like best? add choice remove dice print I love adventures at random
Hedy has to know which list the item should be added to/removed from.
adventures is story, parrot, dice choice is Which adventure do you like best? add choice to adventures remove dice from adventures print I love adventures at random