#Planning a quiz app snap software#
#Planning a quiz app snap code#

#Planning a quiz app snap code#

4.B: Determine the result of code segments.3.B: Use abstraction to manage complexity in a program.3.A: Generalize data sources through variables.2.B: Implement an algorithm in a program.Another common bug is to think that the item variable provided by the block contains an index (an item number), whereas it actually contains the item itself.A very common beginner's bug is to mistrust the for each item block and try to do the traversal in the script in the C-shaped slot.The programmer can just write the code to handle one item, and the block takes care of supplying items one at a time. Understand and use the abstraction of the for each item block, which hides the use of index numbers to access each item.It's easier to understand the design of a computer architecture (the Intel Core design, for example) than to understand the physical circuits that implement it. It's easy to write a program in Snap !, harder to write one in C, because you have to think about more details of memory management. From that perspective, things get harder as you move down the table. It's easier to understand a language than to deal with all the details-how the language is built from lower level languages, and how they work with the computer architecture, and how that's built of transistors, which depend on the behavior of electrons, and so on.

#Planning a quiz app snap software#

In some ways, the physical thing might seem easiest to think about, and the programming at the top of the table harder.Ĭomputer scientists use 'abstract' to mean something more like 'this is defined in terms of that': application software is written in a high level language, which is itself implemented in a low level language. In ordinary language, programming seems to deal with 'more abstract' ideas, things with no visible, tangible existence. In ordinary language, the actual physical computer is the 'least abstract' thing, because you can hold it in your hand, push its buttons, maybe take it apart. (It's not about data abstraction specifically, but the major levels of abstraction in computer science generally.) The table below compares the 'ordinary language' use of abstract with the CS use. At the end, data abstraction itself is defined as the use of abstract data types. Then comes the notion of a data type, and the distinction between primitive types built into the language and abstract types that are specific to one application, rather than a general feature of the programming language. It starts with the most concrete terms, the ones that name procedures you can point to. After the text comes a long vocabulary box that defines six terms.This is the only place where we've used the 'hinting' mechanism on things we want every student to read it's an experiment. Exercise 2 asks students to read the text, clicking links one at a time to look at and then re-hide each code picture. To make it look less intimidating, we have hidden much of the reading behind 'hint' links. This page has more reading, and less doing, than most.An abstract data type consists of a constructor procedure and one or more selector procedures.The when I am clicked block allows a sprite to be used as a button.The empty list is different from a list with an empty item, and is the right starting point when building a list one item at a time.