curriculum.html

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layout: page
title: The BJC Curriculum
call_to_action: Try the Curriculum
call_to_action_link: https://bjc.edc.org/bjc-r/course/bjc4nyc.html
header_background: class2
redirect_from:
  - /website/contact.html
---


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<p>The authors of the BJC curriculum think that computer programming is one of
    the most satisfying of all human activities&mdash;it's generally fun (when
    it's not frustrating because of a bug you can't find), but it's what Seymour
    Papert called "hard fun," mind-stretching and, because the authority is the
    computer rather than the teacher, a big change from jumping through hoops.
    It's a game of skill, like chess, but
    without the competitive aspect, and with useful results beyond the act of
    programming itself.  That's the best reason to study computer science, and we
    want <b>all kids</b>, not just the ones who fit the nerd stereotype, to
    experience our joy in programming.</p>

<p>We also think that computer programs (not just the pictures that programs
    can produce) can be things of beauty.  Yes, programs can also be ugly, if
    they're long sequences of assignment statements with no structure.  But good
    programmers develop a sense of programming aesthetics.  This is one reason why
    it's so important to us to include <em>recursion</em> in the curriculum:
    A recursive program can generate a complex, intricate computing process from a
    very small piece of code, and we remember that revelation as the moment when
    we discovered the beauty of programs.</p>

<p>It's not easy to preserve beauty and joy when translating a course taught
    by its authors into a curriculum for widespread use.  Too much scaffolding in
    a project and the joy is gone; too little scaffolding and the student feels
    helpless and incompetent.  That's why the original authors from the University
    of California, Berkeley, formed a partnership with the high school curriculum
    experts at EDC (Education Development Center).
    <a href="https://bjc.edc.org" target="_blank">Try the
        curriculum</a> to see how you think we did.</p>
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<h2>Computer Science Principles</h2>

<p>The College Board <a
        href="https://advancesinap.collegeboard.org/stem/computer-science-principles" target="_blank">
    AP CS Principles</a>
    curriculum framework is organized around
    seven "Big Ideas" (things to learn) and six "Computational Thinking Practices"
    (things to do):

<p class="centered-strip">
    <img src="{{ site.baseurl }}/assets/img/screenshots/pies_new.png" class="img-responsive"
        alt="Pie Chart of 6 CSP Big Ideas (explained below)">
</p>

<p>Every conforming curriculum must teach all of these, but curricula may
    differ in the amount of emphasis given to each.  (The slices in the pies aren't
    really quantitative, just a suggestive snapshot of how BJC stands out.)
</p>

<p>There is much overlap between the Ideas and the Practices.  Creativity is
    an Idea, but Creating is a Practice.  Similarly, Abstraction is an Idea, but
    Abstracting is a Practice.  Think of the first pie as representing text in the
    curriculum materials, and the second pie as representing how we expect
    students to spend their time.  The circles at the center of each pie indicate
    that the idea of Programming and the practice of Creating are at the center
    of BJC, and intersect with all the others.
</p>

<p>First, the Big Ideas.  BJC is proudly <b><i>Programming</i></b>-heavy.  We
    believe that Snap<i>!</i>, the programming language we use, allows us to reach
    a diverse audience of beginners, who may initially not think they're
    interested in programming, because it combines the ease of use of visual
    programming with expressive power previously found only in the most
    sophisticated text-based languages.  (More on this <a
    href="#visual">below</a>.)  We go far beyond the CS Principles requirements,
    featuring the advanced techniques of recursion and higher order functions.
</p>

<p>We view <b><i>Abstraction</i></b> as the central idea of computer science,
    and we emphasize the use of abstraction in the context of programming.  This
    includes both control abstraction to generalize programming patterns and data
    abstraction to isolate the implementation of an abstract data type from its
    use.
</p>

<p>Our secondary emphasis is on <b><i>Global Impact</i></b>, the social
    implications of computing.  We use readings and classroom discussion to
    explore various aspects of this topic in each unit of the course.
    Details of the topics and teaching goals are <a href="#social">below</a>.
</p>

<p>Two of the remaining four topics are more implicit than explicit in our
    approach.  Students <i>exercise</i> <b>Creativity</b> in their programming
    projects, but we don't <i>talk about</i> it to the same extent as the other
    topics.  Similarly, students <i>develop</i> <b>Algorithms</b> as they program,
    but we don't often treat algorithms as a separate topic, except when we are
    teaching about analysis of algorithms and asymptotic orders of growth.
</p>

<p>The final category of topics, <b>Data</b> and <b>the Internet</b>, are
    important and are covered thoroughly, but where possible our coverage takes
    the form of programming activities rather than, for example, using commercial
    database software.
</p>

<p>Now, about the Practices:  The phrase "Computational Artifacts" is
    meant to encompass videos, slide decks, blogs, programs, music,
    spreadsheets&mdash;anything you can create with a computer.  Creating is, we
    think, by far the most important of the Practices, but the most important
    artifacts are computer programs!  More precisely, if a student is writing a
    game program, for example, there are two acts of creation happening at once.
    The student is interested in making a game, and displays creativity in the
    design of the game.  But she creates the game by creating a program, and
    <em>also</em> displays creativity in the design of the program structure.
    And the latter is the real computer science.
</p>

<p>Just as the idea of abstraction is central to, and inseparable from, the
    idea of programming, the <em>practice</em> of abstraction is central to
    programming.  We constantly encourage students to use layers of abstraction to
    structure a programming project.
</p>

<p>"Connecting computing" can mean connecting it to hobbies, or connecting it
    to industry, or to science.  But most importantly, for us, students connect
    computing to its social implications, our secondary focus.
</p>

<p>Almost as important is the practice of analyzing programs: debugging,
    predicting the behavior of someone else's code, and thinking about efficiency.
    But we would emphasize that this skill is not an end in itself; it serves the
    ultimate goal of creating programs that work.  We're not nearly as interested
    in analyzing "artifacts" other than programs.
</p>

<p>The two remaining practices are important, but less emphasized in BJC.
    Like most CSP curricula, we use pair programming, so students are constantly
    talking with their partners and sharing the work.  At the beginning of the
    course we teach the process of pair programming, and in the discussion of
    social implications of computing students have to communicate their ideas, but
    communicating and collaborating aren't unique to computer science.
</p>
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<a class="anchor" id="visual"></a>
<h2>Visual Programming</h2>

<p><a href="https://snap.berkeley.edu" target="_blank">Snap<i>!</i></a>, the programming
    language designed to support this course, starts with the <a
            href="https://scratch.mit.edu" target="_blank">Scratch</a> design of drag-and-drop blocks
    representing primitive capabilities.  Scratch is routinely learned by
    self-taught eight-year-olds, so it's not intimidating and has a very low
    barrier to entry. The blocks' shapes and colors remind users of
    the block categories.</p>

<p class="centered-strip">
    <img src="{{ site.baseurl }}/assets/img/screenshots/flagsquare.png" class="img-responsive"
        alt="Snap! programing showing how to draw a sqaure using repeat"/>
</p>

<p>The C-shaped block is a loop, and visually encloses the code that should be
    repeated.  Green blocks are about drawing, and blue blocks are about motion.
</p>

<p>But because Scratch was designed to be usable by eight-year-olds, its
    designers left out some key capabilities for teaching computer science.
    Snap<i>!</i> adds the needed abstraction capabilities, while preserving the
    use of carefully designed visual metaphors to aid understanding:
</p>

<hr />

<p>For control abstraction, Snap<i>!</i> users can build their own
    blocks, including functions as well as action scripts.
</p>

<p class="centered-strip">
    <img src="{{ site.baseurl }}/assets/img/screenshots/makeablock.png" class="side-by-side img-responsive"
        alt="Snap! make a block dialog" />
    <img src="{{ site.baseurl }}/assets/img/screenshots/blockeditor.png" class="side-by-side img-responsive"
        alt="Snap! block editor dialog" />
    <img src="{{ site.baseurl }}/assets/img/screenshots/scriptwithblock.png" class="side-by-side img-responsive"
        alt="Snap! script using when green flag clicked"/>
</p>

<p>This capability is essential to the Abstraction big idea, but it
    also lets us teach recursion, through which a small program can
    have a very complex result:
</p>

<p class="centered-strip">
    <img src="{{ site.baseurl }}/assets/img/screenshots/livetree.png" class="img-responsive side-by-side"
        alt="Snap! Script of a `tree` block to draw a fractal" />
    <img src="{{ site.baseurl }}/assets/img/screenshots/treepic.png" class="img-responsive side-by-side"
        alt="A tree fractal drawn by the tree block" />
</p>

<p>Because Snap<i>!</i> blocks can take other blocks or scripts as
    inputs, and because of the very simple notation used for anonymous functions,
    we can teach the even more powerful control abstraction of higher order
    functions:
</p>

<p class="centered-strip">
    <img src="{{ site.baseurl }}/assets/img/screenshots/plusfour.png" class="img-responsive"
        alt="Snap! Code: map plus 4 over a list of 3 numbers" />
</p>

<p>This capability, first class procedures, makes Snap<i>!</i> more powerful
    and expressive than most text-based programming languages.  The visual
    representation makes procedure as data seem concrete to students, as in this
    <em>list of procedures:</em>
</p>

<p class="centered-strip">
    <img src="{{ site.baseurl }}/assets/img/screenshots/blocks.png" class="img-responsive"
        alt="3 blocks inside a Snap! list" />
</p>

<hr />

<p>Finally, because lists are first class data in Snap<i>!</i>, we
    can build abstract data types and use them in larger data structures, such as
    this triangle:
</p>

<p class="centered-strip">
    <img src="{{ site.baseurl }}/assets/img/screenshots/pointlist.png" class="img-responsive"
        alt="A Snap! program showing a list of 3 items using the point block" />
</p>

<hr />

<p>For students who insist on programming in a text language,
    Snap<i>!</i> provides access to the Javascript environment in which it is
    implemented:
</p>

<p class="centered-strip">
    <img src="{{ site.baseurl }}/assets/img/screenshots/speakblock.png" class="img-responsive"
        alt="A Snap! speach to text block using JavaScript" />
</p>

<p>(The picture shows a one-liner, but there is no limit to the length or
    complexity of the Javascript function defined by the block.) With this
    capability we can have our cake and eat it too, with respect to the
    (pointless, we think) argument about block languages vs. text languages.
    We don't teach Javascript in BJC, but it's available as an enrichment
    activity if needed.
</p>

<p>Also, since Snap<i>!</i> runs in any modern browser, students can make
    mobile apps for iOS or Android by putting a shortcut to the project's URL on
    the device's desktop.  From the browser we can't access phone-specific
    information such as contact list or GPS position (standalone versions are in
    the works), but things like video game projects work fine.
</p>

<p>Snap<i>!</i> also connects with several robots and sensors (Finch,
    Hummingbird, Sphero, Lego NXT, Wiimote, LEAP Motion, Arduino, etc.) by way of
    small applications installed on the local computer.
</p>
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<a class="anchor" id="social"></a>
<h2>Social Implications of Computing</h2>

<div class="side-by-side">
    <p>
        Here are the topics included in the BJC units:
    </p>
    <ul>
        <li>Privacy and Search Engines</li>
        <li>Video Games and Violence</li>
        <li>Owning Ideas (Copyrights and Patents)</li>
        <li>Encryption</li>
        <li>Innovation</li>
        <li>Computers and Community
            <ul>
                <li>Social networks</li>
                <li>Cyberbullying</li>
            </ul>
        </li>
        <li>Computers and War</li>
        <li>Computers and Work</li>
    </ul>
</div>
<div class="pull-right">
    <img src="{{ site.baseurl }}/assets/img/blown-to-bits.png" height="250px"
        alt="Cover of the Blown to Bits book" />
</div>

<p>In all of these topics, our goal is to avoid preaching; we look for
    alternate points of view.  For example, we don't assume that pirating
    copyrighted works is wrong; since many students do it, we try to elicit honest
    perspectives on why it might be okay, and consider alternate ways to support
    artists and writers.  Both student pages and the Teachers' Guide point to
    provocative readings on each topic.
</p>

<p>In general, we hope to leave students feeling optimistic about the benefits
    of technology, but also ready to think critically about any <i>specific</i>
    technology.  We also remind them that the decisions about how a new technology
    is used are made by human beings, including themselves if they pursue a career
    in computer science, so they shouldn't feel helpless in the face of a supposed
    technological imperative.
</p>

<p>We use the excellent <a href="https://bitsbook.com" target="_blank"><i>Blown to Bits</i></a>
    as the textbook for this part of the course.  (There is no textbook for the
    technical parts of the course, beyond the online materials we provide.)  The
    book is aimed at adult readers, and will be difficult especially for ESL
    students, so we use short excerpts and discuss alternative presentations in
    the Teachers' Guide.  Like the rest of the course materials, this book is
    avaliable free online, with a Creative Commons BY-NC-SA license.
</p>

<p>The book is a few years old now, so we supplement it with current readings,
    looking for topics that will be relevant to students.  Students choose their
    own topics to study in more depth; this is one way we appeal to a diverse
    audience.  We start class meetings
    with "Computing in the News," presenting items from that morning's newspaper,
    one generally positive and one problematic.  After some teacher-chosen
    examples to illustrate the idea, we encourage teachers to assign the selection
    of articles to students in rotation.
</p>
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<h2>About Snap<i>!</i></h2>

<p class="pull-right hidden-xs">
    <img src="{{ site.baseurl }}/assets/img/partners/snap.png" class="img-responsive"
        alt="Snap! logo" />
</p>

<p>
    Snap<em>!</em> is a visual programming language based on
    <a href="https://scratch.mit.edu" target="_blank">Scratch</a> (MIT Media Lab), but
    <a href="https://snap.berkeley.edu/about" target="_blank">extended</a>
    to support more advanced computer science ideas, especially
    recursion and functional programming.
</p>

<ul>
    <li>
        <a href="https://snap.berkeley.edu" target="_blank">Snap<em>!</em> Home Page</a>
    </li>
    <li>
		<a href="https://snap.berkeley.edu/snap/help/SnapManual.pdf" target="_blank">Snap<em>!</em> Manual</a>
    </li>
    <li>
        <a href="https://snap.berkeley.edu/run" target="_blank">Run Snap<em>!</em> Live</a>
    </li>
    <li>
        Snap<i>!</i> Projects:
        <ul>
            <li><a href="https://snap.berkeley.edu/snapsource/snap.html#present:Username=bh&ProjectName=vee" target="_blank">Vee</a></li>
            <li><a href="https://snap.berkeley.edu/snapsource/snap.html#open:https://snap.berkeley.edu/snapsource/demo/treedemo.xml" target="_blank">Tree Demo</a></li>
            <li><a href="https://snap.berkeley.edu/snapsource/snap.html#open:https://snap.berkeley.edu/snapsource/demo/live-tree.xml" target="_blank">Live Tree</a></li>
            <li><a href="https://snap.berkeley.edu/snapsource/snap.html#open:https://snap.berkeley.edu/snapsource/demo/palindrome.xml" target="_blank">Palindrome Exercise</a></li>
            <li><a href="https://snap.berkeley.edu/snapsource/snap.html#open:https://snap.berkeley.edu/snapsource/demo/count-change.xml" target="_blank">Count Change</a></li>
        </ul>
    </li>
    <li>
        <a href="https://forum.snap.berkeley.edu/c/bugs/7" target="_blank">Report a Snap<em>!</em> bug</a>
    </li>
</ul>
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