One way to do this is create a spreadsheet in your Google account, and then share it with everyone involved. That way people can collaborate together and edit it.
Create a column for each person with their list of tasks. Then have a “status column” so each person can keep track of their progress.
Make it a shared document, allowing for your boss and co-workers to view as well. That way, when two people are both working on the same assignment, they have an easy way to collaborate with each other. We have found, at HireAHelper, that this is the best way to keep things organized and the most efficient way to make sure tasks are getting done.