2nd Grade:

Stop the Clock
http://www.teachingtime.co.uk/draggames/sthec3.html

Clockwise
http://www.bbc.co.uk/education/dynamo/den/clock/index.htm

Just in Time
http://www.fi.edu/time/Journey/JustInTime/contents.html

Time Clock
http://www.primarygames.com/math/timeclock/index.htm

Ordinal Numbers
http://www.primarygames.com/squigly/question1.htm

3rd Grade
Stop the Clock
http://www.teachingtime.co.uk/draggames/sthec3.html

Clockwise
http://www.bbc.co.uk/education/dynamo/den/clock/index.htm

Just in Time
http://www.fi.edu/time/Journey/JustInTime/contents.html

Time Clock
http://www.primarygames.com/math/timeclock/index.htm

4th Grade

The Underground Railroad
http://teacher.scholastic.com/activities/bhistory/underground_railroad/plantation.htm