This set of three worksheets are focused on estimating the activities that can be completed within given durations.   From simple activities measured in seconds and minutes to more complex ones spanning decades and centuries, your students will sharpen their time estimation skills. With three versions catering to different units of time, these worksheets can be used to differentiate instruction or as a progressive learning tool. When you have decided which versions to give to which students, you can simply print out the number of copies that you require.   Potential answers are provided, though they will vary, encouraging critical thinking and discussion.