diff --git a/README.md b/README.md
index 846b88e..2873c02 100644
--- a/README.md
+++ b/README.md
@@ -10,6 +10,13 @@ It is written in Ruby.
 Installation
 ------------
 
+kgrader was developed using Ruby 2.2, though it should work with any recent
+version of Ruby.
+
+Install dependencies with gem:
+
+    gem install ruby-progressbar
+
 Download kgrader over git:
 
     git clone https://github.com/earwig/kgrader.git kgrader
diff --git a/lib/kgrader/cli.rb b/lib/kgrader/cli.rb
index 4a87c3e..d14e772 100644
--- a/lib/kgrader/cli.rb
+++ b/lib/kgrader/cli.rb
@@ -24,21 +24,21 @@ module KGrader
       course.roster(semester).load rosterfile
     end
 
-    def grade(course, semester, assignment, options = {})
+    def grade(course, semester, assignment, students = nil, options = {})
       course = Course.new(@fs, course)
       semester ||= course.current_semester
-      course.task(semester, assignment).grade options
+      course.task(semester, assignment, students).grade options
     end
 
-    def commit(course, semester, assignment, options = {})
+    def commit(course, semester, assignment, students = nil)
       course = Course.new(@fs, course)
       semester ||= course.current_semester
-      course.task(semester, assignment).commit options
+      course.task(semester, assignment, students).commit
     end
 
     def clean
-      # TODO: also purge uncommitted grades
       clear_jail
+      # TODO: also purge uncommitted grades: set all graded to ungraded and delete all pending files
     end
 
     def clobber
diff --git a/lib/kgrader/course.rb b/lib/kgrader/course.rb
index a80fab1..1e50045 100644
--- a/lib/kgrader/course.rb
+++ b/lib/kgrader/course.rb
@@ -23,8 +23,8 @@ module KGrader
       @assignments[name] ||= Assignment.new @fs, self, name
     end
 
-    def task(semester, assignment)
-      Task.new @fs, self, semester, assignment
+    def task(semester, assignment, students = nil)
+      Task.new @fs, self, semester, assignment, students
     end
 
     def rosters
diff --git a/lib/kgrader/roster.rb b/lib/kgrader/roster.rb
index 81a601f..cc6f43f 100644
--- a/lib/kgrader/roster.rb
+++ b/lib/kgrader/roster.rb
@@ -10,7 +10,7 @@ module KGrader
     end
 
     def load(filename)
-      @students = @fs.load(filename).map! { |item| item.first }
+      @students = @fs.load(filename).map! &:first
       FileUtils.mkdir_p File.dirname(rosterfile)
       File.write rosterfile, @students.join("\n")
     rescue FilesystemError => err
@@ -18,7 +18,7 @@ module KGrader
     end
 
     def students
-      @students ||= @fs.load(rosterfile).map! { |item| item.first }
+      @students ||= @fs.load(rosterfile).map! &:first
     rescue FilesystemError
       raise RosterError, "unknown semester: #{semester}"
     end
diff --git a/lib/kgrader/submission.rb b/lib/kgrader/submission.rb
index 3b66c2b..48a876c 100644
--- a/lib/kgrader/submission.rb
+++ b/lib/kgrader/submission.rb
@@ -29,6 +29,7 @@ module KGrader
     def create
       FileUtils.mkdir_p @root
       self.status = :init
+      nil
     end
 
     def fetch(due)
@@ -43,20 +44,48 @@ module KGrader
         rewind due
         self.status = revision == oldrev ? :graded : :ungraded
       end
+      nil
     end
 
     def grade
-      # TODO
+      # TODO:
+      # self.status = :ungraded
+      # [grade the stuff]
+      # [save report to gradefile]
+      # FileUtils.touch pendingfile
       # self.status = :graded
+      # return grade summary string
+
+      sleep rand / 2
+      '100%'
+    end
+
+    def commit
+      # TODO:
+      # if status == :graded && File.exists? pendingfile
+      #   [copy gradefile to repo and commit]
+      #   FileUtils.rm pendingfile
+      # end
+
+      sleep rand / 2
+      nil
     end
 
     private
+    def repo
+      File.join @root, "repo"
+    end
+
     def statusfile
       File.join @root, "status.txt"
     end
 
-    def repo
-      File.join @root, "repo"
+    def gradefile
+      File.join @root, "grade.txt"
+    end
+
+    def pendingfile
+      File.join @root, "pending"
     end
 
     def revision
diff --git a/lib/kgrader/task.rb b/lib/kgrader/task.rb
index f13d7bb..7ede464 100644
--- a/lib/kgrader/task.rb
+++ b/lib/kgrader/task.rb
@@ -1,64 +1,71 @@
+require 'ruby-progressbar'
+
 module KGrader
   class Task
 
-    def initialize(filesystem, course, semester, assignment)
-      @fs         = filesystem
-      @course     = course
-      @semester   = semester
-
-      @assignment = @course.assignment assignment
-      @students   = @course.roster(@semester).students
+    def initialize(filesystem, course, semester, assignment, students = nil)
+      @fs          = filesystem
+      @course      = course
+      @semester    = semester
+      @assignment  = @course.assignment assignment
+      @submissions = get_submissions students
     end
 
     def grade(options = {})
-      submissions = get_submissions options[:students]
       due = options.fetch(:due, Time.now)
       fetch = options.fetch(:fetch, true)
       regrade = options.fetch(:regrade, false)
 
-      count = submissions.count
-      puts "[grading #{count} student#{'s' if count != 1}]"
-
-      submissions.each do |sub|
-        unless sub.exists?
-          puts "[init #{sub.student}]"
-          sub.create
-        end
+      subtask 'setup' do |sub|
+        sub.create unless sub.exists?
       end
 
       if fetch
-        submissions.each do |sub|
-          puts "[fetch #{sub.student}]"
+        subtask 'fetch' do |sub|
           sub.fetch due
         end
       end
 
-      submissions.each do |sub|
-        sub.status = :ungraded if regrade
-        if sub.status == :ungraded
-          puts "[grade #{sub.student}]"
+      subtask 'grade' do |sub|
+        if sub.status == :init || sub.status == :fetching
+          next 'skip (need to fetch first)'
+        elsif sub.status == :graded && !regrade
+          next
+        else
           sub.grade
         end
       end
     end
 
-    def commit(options = {})
-      submissions = get_submissions options[:students]
-
-      # TODO
-      puts "[committing]"
-      puts "course     => #{@course.name}"
-      puts "semester   => #{@semester}"
-      puts "assignment => #{@assignment.name}"
-      puts "students   => #{submissions.map { |sub| sub.student }.join ', '}"
+    def commit
+      subtask 'commit', &:commit
     end
 
     private
     def get_submissions(students)
-      students.nil? ? (students = @students) : (students &= @students)
+      roster = @course.roster(@semester).students
+      students.nil? ? (students = roster) : (students &= roster)
       students.map do |student|
         Submission.new @fs, @course, @semester, @assignment, student
       end
     end
+
+    def student_len
+      @student_len ||= @submissions.map { |sub| sub.student.length }.max
+    end
+
+    def subtask(name)
+      progress = ProgressBar.create title: name, total: @submissions.size,
+        throttle_rate: 0, format: '%t [%b>%i] %j%% %e    '
+
+      @submissions.each.with_index do |sub, i|
+        job = "#{name} [#{sub.student.ljust student_len}]"
+        progress.title = "#{job}:"
+        result = yield sub
+        progress.title = name if i == @submissions.size - 1
+        progress.log "#{job}#{': ' if result}#{result}" if result
+        progress.increment
+      end
+    end
   end
 end
diff --git a/rakefile b/rakefile
index dbb412b..65157ab 100644
--- a/rakefile
+++ b/rakefile
@@ -45,13 +45,15 @@ task :grade do
   course, assignment, options = parse_args 2..2,
     { :semester => :string, :students => :array, :due => :time,
       :fetch => :bool, :regrade => :bool }
-  run { |cli| cli.grade course, options[:semester], assignment, options }
+  semester, students = options[:semester], options[:students]
+  run { |cli| cli.grade course, semester, assignment, students, options }
 end
 
 task :commit do
   course, assignment, options = parse_args 2..2,
     { :semester => :string, :students => :array }
-  run { |cli| cli.commit course, options[:semester], assignment, options }
+  semester, students = options[:semester], options[:students]
+  run { |cli| cli.commit course, semester, assignment, students }
 end
 
 task :clean do