This snippet gives a web2py scaffolding form for student attendance

    Copyright (C) 2013  Alan Etkin

    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU Affero General Public License as
    published by the Free Software Foundation, either version 3 of the
    License, or (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU Affero General Public License for more details.

    You should have received a copy of the GNU Affero General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.

       Affero GPLv3 License

The model

DAYS = ["2013-01-22", "2013-02-22", "2013-03-22",
        "2013-04-22", "2013-05-22", "2013-06-22"]
STUDENTS = dict([(student.id, "%s %s" % (student.first_name,
                                         student.last_name)) for
                                         student in db(db.auth_user).select()])

db.define_table("attendance",
                Field("student", "reference auth_user"), 
                Field("day", requires=IS_IN_SET(DAYS)))

ATTENDANCES = ["%s_%s" % (attendance.day,
                          attendance.student) for
               attendance in db(db.attendance).select()]

def attended(day, student_id):
    s = "%s_%s" % (day, student_id)
    return s in ATTENDANCES

The controller

def attendance():
    head = THEAD(TR([TD(), *TD(day) for day in DAYS]))
    body = TBODY(*[TR(TD("%s %s" % (student.first_name, student.last_name)),
                      *[TD(INPUT(value=attended(day, student.id),
                                 _type="checkbox",
                                 _name="%s_%s" % (day, student.id))) for
                                 day in DAYS]) for student in STUDENTS])
    form = FORM(TABLE(head, body))
    if form.process().accepted:
        # Here you must check changes and apply them to the db
        for k, v in form.vars.iteritems():
            day, student_id = k.split("_")
            if (not k in ATTENDANCES) and v:
                db.attendance.insert(student=student_id,
                                     day=day)
            elif k in ATTENDANCES and not v:
                db((db.attendance.student==student_id)&\
                   (db.attendance.day==day)).delete()
    return dict(form=form)

The view

{{=form}}