Physics Teaching for the 21st Century (://c21.phas.ubc.ca) is a free online resource for teachers who are interested in teaching physics concepts in real-world contexts. The materials on this site were developed by a team of physics faculty and graduate and undergraduate students at the Department of Physics & Astronomy, University of British Columbia, based on issues of great current concern—reusable energy, climate change, and medical advancement. Topics on the website also focus on applications of physics in the natural world around us. There are currently about 70 different topics on the website and it is not possible to justly give a sense of the website in total here. Instead we will present one complete example of the resources available on our website and show how it can be used in the classroom or in lecture. The example discussed here1 is suitable for a first-year university course and focuses on diffraction through a circular aperture and Rayleigh's resolution criterion by looking at the effect of pupil size on the minimum angle of resolution. The original idea came from reading a book on zoological physics,2 and a short example was later found in a first-year physics textbook.3

2.
B. K.
Ahlborn
,
Zoological Physics
(
Springer-Verlag Berlin
,
Heidelberg
,
2004
), p.
276
.
3.
R. D.
Knight
,
B.
Jones
, and
S.
Field
,
College Physics: A Strategic Approach
, 2nd ed. (
Addison-Wesley
,
2007
), p.
629
.
4.

Each main article on the website comes with an interesting header, or “hook,” and “big ideas.”

6.
R. D.
Knight
,
Physics for Scientists and Engineers: A Strategic Approach
, 2nd ed. (
Pearson Addison-Wesley
,
2008
), p.
685
.
8.
O. E.
Lind
,
A.
Kelber
, and,
R. H. H.
Kroger
, “
Multifocal optical systems and pupil dynamics in birds
,”
J. Exp. Biol.
211
,
2752
2758
(
2008
).
9.
C. A.
Curcio
,
K. R.
Sloan
,
R. E.
Kalina
, and
A. E.
Hendrickson
, “
Human photoreceptor topography
,”
J. Comp. Neurol.
292
,
497
523
(
1990
).
10.
L.
Reymond
, “
Spatial visual acuity of the eagle Aquila Audax: A behavioural, optical and anatomical investigation
,”
Vis. Res.
25
,
1477
1491
(
1985
).
11.
W. J.
Donnelly
 III
and
A.
Roorda
, “
Optimal pupil size in the human eye for axial resolution
,”
J. Opt. Soc. Am. A
20
,
2010
2015
(
2003
).
12.
M.
Yanoff
and
J. S.
Duker
,
Opthalmology
(
Elsevier Inc.
,
2009
), p.
54
.
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