<s>
The	O
ProgramByDesign	B-Language
(	O
formerly	O
TeachScheme	B-Language
!	I-Language
)	O
</s>
<s>
project	O
is	O
an	O
outreach	O
effort	O
of	O
the	O
PLT	B-Operating_System
research	O
group	O
.	O
</s>
<s>
The	O
goal	O
is	O
to	O
train	O
college	O
faculty	O
,	O
high	O
school	O
teachers	O
,	O
and	O
possibly	O
even	O
middle	O
school	O
teachers	O
,	O
in	O
programming	B-General_Concept
and	O
computing	O
.	O
</s>
<s>
Matthias	O
Felleisen	O
and	O
PLT	B-Operating_System
began	O
the	O
effort	O
in	O
January	O
1995	O
,	O
one	O
day	O
after	O
the	O
Symposium	O
on	O
Principles	O
of	O
Programming	B-General_Concept
Languages	O
(	O
POPL	O
)	O
,	O
in	O
response	O
to	O
Felleisen	O
's	O
observations	O
of	O
his	O
Rice	O
University	O
freshmen	O
students	O
and	O
the	O
algebra	O
curriculum	O
of	O
local	O
public	O
schools	O
.	O
</s>
<s>
His	O
objective	O
was	O
to	O
use	O
functional	B-Language
programming	I-Language
to	O
make	O
mathematics	O
come	O
alive	O
and	O
help	O
inject	O
design	O
knowledge	O
into	O
the	O
introductory	O
computer	B-General_Concept
science	I-General_Concept
curriculum	O
.	O
</s>
<s>
The	O
effort	O
began	O
using	O
a	O
programming	B-General_Concept
language	O
named	O
PLT	B-Operating_System
Scheme	I-Operating_System
which	O
was	O
a	O
version	O
of	O
the	O
language	O
Scheme	B-Language
,	O
which	O
is	O
a	O
dialect	O
of	O
Lisp	B-Language
.	O
</s>
<s>
In	O
2005	O
,	O
the	O
TeachScheme	B-Language
!	I-Language
</s>
<s>
In	O
2010	O
,	O
PLT	B-Operating_System
renamed	O
its	O
major	O
programming	B-General_Concept
language	O
from	O
PLT	B-Operating_System
Scheme	I-Operating_System
to	O
Racket	B-Operating_System
,	O
and	O
DrScheme	B-Operating_System
to	O
DrRacket	B-Operating_System
.	O
</s>
<s>
A	O
little	O
later	O
it	O
renamed	O
TeachScheme	B-Language
!	I-Language
</s>
<s>
to	O
ProgramByDesign	B-Language
.	O
</s>
<s>
The	O
starting	O
point	O
of	O
ProgramByDesign	B-Language
is	O
the	O
observation	O
that	O
students	O
act	O
as	O
computers	O
in	O
primary	O
school	O
courses	O
on	O
arithmetic	O
,	O
and	O
in	O
middle	O
school	O
and	O
secondary	O
school	O
courses	O
on	O
pre-algebra	O
and	O
algebra	O
.	O
</s>
<s>
The	O
key	O
is	O
that	O
students	O
execute	O
purely	O
functional	B-Language
programs	I-Language
.	O
</s>
<s>
If	O
students	O
can	O
be	O
turned	O
into	O
teachers	O
that	O
create	O
functional	B-Language
programs	I-Language
and	O
run	O
them	O
on	O
computers	O
,	O
this	O
content	O
can	O
be	O
reinforced	O
and	O
show	O
students	O
how	O
writing	O
down	O
mathematics	O
,	O
and	O
functional	B-Language
programs	I-Language
,	O
creates	O
lively	O
animated	O
scenes	O
and	O
even	O
computer	O
games	O
.	O
</s>
<s>
The	O
background	O
needed	O
for	O
such	O
an	O
example	O
is	O
little	O
more	O
than	O
knowledge	O
about	O
making	O
movies	O
,	O
about	O
the	O
algebra	O
of	O
pictures	O
in	O
DrRacket	B-Operating_System
(	O
which	O
is	O
like	O
the	O
one	O
for	O
numbers	O
)	O
,	O
and	O
minimal	O
pre-algebra	O
.	O
</s>
<s>
The	O
ProgramByDesign	B-Language
project	O
claims	O
,	O
however	O
,	O
that	O
children	O
would	O
have	O
more	O
fun	O
with	O
such	O
live	O
functions	O
than	O
with	O
algebraic	O
expressions	O
that	O
count	O
the	O
number	O
of	O
garden	O
tiles	O
[	O
see	O
Prentice	O
Hall	O
books	O
for	O
grades	O
8-9	O
]	O
.	O
</s>
<s>
The	O
ProgramByDesign	B-Language
project	O
proposes	O
that	O
both	O
traditional	O
mathematics	O
and	O
science	O
courses	O
could	O
benefit	O
from	O
integrating	O
this	O
form	O
of	O
programming	B-General_Concept
.	O
</s>
<s>
In	O
contrast	O
to	O
the	O
traditional	O
BASIC	O
or	O
Visual	B-Language
Basic	I-Language
blocks	O
in	O
such	O
books	O
,	O
a	O
Racket	B-Operating_System
program	O
consists	O
of	O
as	O
many	O
lines	O
as	O
the	O
mathematics	O
.	O
</s>
<s>
DrRacket	B-Operating_System
's	O
algebraic	O
stepper	O
can	O
illustrate	O
how	O
Racket	B-Operating_System
evaluates	O
the	O
program	O
as	O
if	O
it	O
were	O
a	O
sixth	O
or	O
seventh	O
grade	O
student	O
,	O
step	O
by	O
step	O
,	O
using	O
plain	O
algebra	O
.	O
</s>
<s>
For	O
the	O
introductory	O
curriculum	O
on	O
programming	B-General_Concept
,	O
the	O
ProgramByDesign	B-Language
project	O
emphasizes	O
that	O
courses	O
should	O
focus	O
on	O
the	O
role	O
of	O
systematic	O
design	O
.	O
</s>
<s>
Thus	O
,	O
an	O
introductory	O
course	O
in	O
programming	B-General_Concept
would	O
not	O
be	O
perceived	O
as	O
a	O
place	O
where	O
students	O
learn	O
about	O
the	O
syntax	O
of	O
the	O
currently	O
fashionable	O
(	O
and	O
soon-to-be-obsolete	O
)	O
programming	B-General_Concept
languages	O
,	O
but	O
a	O
place	O
where	O
they	O
can	O
learn	O
something	O
widely	O
applicable	O
.	O
</s>
<s>
The	O
key	O
design	O
element	O
of	O
the	O
ProgramByDesign	B-Language
curriculum	O
is	O
the	O
design	O
recipe	O
.	O
</s>
<s>
How	O
to	O
Design	O
Programs	O
(	O
HTDP	O
)	O
is	O
the	O
text	O
book	O
authored	O
by	O
the	O
core	O
of	O
the	O
ProgramByDesign	B-Language
group	O
.	O
</s>
<s>
The	O
name	O
TeachScheme	B-Language
!	I-Language
</s>
<s>
appears	O
to	O
imply	O
that	O
this	O
design	O
recipe	O
requires	O
Scheme	B-Language
(	O
now	O
Racket	B-Operating_System
)	O
and	O
is	O
teachable	O
only	O
with	O
Scheme	B-Language
.	O
</s>
<s>
Members	O
of	O
PLT	B-Operating_System
and	O
their	O
trainees	O
have	O
successfully	O
applied	O
the	O
design	O
recipe	O
in	O
assembly	B-Language
language	I-Language
,	O
C	B-Language
,	O
Java	B-Language
,	O
ML	B-Language
,	O
Python	B-Language
,	O
and	O
other	O
programming	B-General_Concept
languages	O
,	O
and	O
with	O
geometry	O
,	O
biology	O
,	O
and	O
poetry	O
courses	O
.	O
</s>
<s>
The	O
fundamental	O
idea	O
of	O
ProgramByDesign	B-Language
is	O
to	O
stress	O
programming	B-General_Concept
as	O
a	O
design	O
activity	O
.	O
</s>
<s>
To	O
get	O
started	O
,	O
the	O
ProgramByDesign	B-Language
project	O
has	O
produced	O
three	O
essential	O
elements	O
:	O
</s>
<s>
Their	O
choice	O
of	O
Racket	B-Operating_System
reflects	O
their	O
belief	O
that	O
Racket	B-Operating_System
is	O
a	O
good	O
language	O
for	O
a	O
small	O
team	O
with	O
little	O
funding	O
(	O
relative	O
to	O
Java	B-Language
)	O
to	O
validate	O
their	O
conjectures	O
.	O
</s>
<s>
The	O
PLT	B-Operating_System
group	O
has	O
always	O
tried	O
to	O
ensure	O
that	O
the	O
ideas	O
remain	O
portable	O
to	O
other	O
contexts	O
.	O
</s>
<s>
It	O
demonstrates	O
how	O
the	O
same	O
design	O
recipe	O
ideas	O
apply	O
to	O
a	O
complex	O
object-oriented	B-Language
programming	I-Language
language	I-Language
,	O
such	O
as	O
Java	B-Language
.	O
</s>
<s>
The	O
recipes	O
are	O
applied	O
initially	O
in	O
a	O
functional	B-Language
paradigm	I-Language
,	O
then	O
introducing	O
object-oriented	B-Language
concepts	O
such	O
as	O
polymorphism	O
and	O
inheritance	O
,	O
and	O
then	O
introducing	O
the	O
imperative	O
methods	O
that	O
are	O
idiomatic	O
in	O
mainstream	O
Java	B-Language
.	O
</s>
<s>
In	O
2006	O
PLT	B-Operating_System
,	O
at	O
Northeastern	O
University	O
and	O
Citizen	O
Schools	O
from	O
Boston	O
,	O
made	O
joint	O
efforts	O
to	O
reach	O
out	O
to	O
inner	O
city	O
students	O
with	O
after-school	O
programs	O
.	O
</s>
<s>
The	O
effect	O
on	O
the	O
mathematics	O
courses	O
of	O
this	O
program	O
has	O
encouraged	O
Microsoft	O
and	O
Google	B-Application
to	O
fund	O
a	O
national	O
scale-up	O
effort	O
,	O
developing	O
materials	O
for	O
training	O
teachers	O
and	O
creating	O
sites	O
in	O
Texas	O
,	O
California	O
,	O
and	O
other	O
volunteer	O
cities	O
.	O
</s>
