Verb conjugation of "tarder" in French

In order to improve the language skills we changed some features on Vocabulix. From now on users can not only drill isolated lesson but adhere to a specific lesson plan. That means that they can set goals and seek help from other users.
Vocabulix includes a vocabulary builder for many languages, Spanish and German are just the ones that have the predefined sections. Generally speaking you can invent your own set of expressions and drill them on the speed train.
I really would like to invest more time here but until now I was too busy to keep my promises. Maybe I should take a vacation and go back to Scotland and take another language course there.