There are two Practice buttons, one for the full course and one for every skill.
Global Practice iconEdit
The global practice icon appears after you are in level 1 of the introduction.
Where to find itEdit
Desktop web browser: A circle with a blue dumbbell icon that floats on the lower left of the tree.
Mobile web browser and Android app: A circle with a blue dumbbell icon that floats on the bottom right of the page.
iOS app: the lower menu has a heart icon that goes to the Health page. There a button labeled "Earn Practice" or "1 Heart Practice" can be found. Some courses (so far seen in Navajo for English and Esperanto for Portuguese) instead of a heart icon have a dumbbell icon.
The Practice button for the full course (previously named Strengthen skills) provides a number  of exercises reviewing material learned in lessons, with a focus on the material that Duolingo believes the user most needs practice in at that moment. Such practices are untimed by default; however, a timed practice option is also available for purchase in the Lingot store. Untimed tests always earn the user a minimum of 3XP, and a maximum of 10XP.
How it worksEdit
A practice session may result in strengthening the words practiced, and if enough words from the same skill are strengthened, also strengthening one or more related skills. So "it is very possible that practicing one skill can strengthen another skill". A session doesn't necessarily need to be completed successfully in order to strengthen skills, especially if one uses a timed practice . However, it may take more than one try to fully strengthen a skill (e.g. make it gold).
According to Duolingo, "learners should first focus on finishing all the lessons in a skill, and later come back to review them at just the right times".
Global Practice button helps users to:
- Test their knowledge;
- Review learnt material; and
- Maintain and improve their skills.
Global Practice shows a message and doesn't allow more practice when :
Algorithm thinks your words are all fresh.
When a skill is completed, i.e. when it is in level 5, the Practice button appears.
Where to find itEdit
Press the skill icon and a small window appears with a white button labeled "Practice" in gold letters.
- ↑ https://www.duolingo.com/comment/851887$comment_id=852730
- ↑ https://www.duolingo.com/comment/1052217$comment_id=1064050
- ↑ https://www.duolingo.com/comment/878880$comment_id=882596
- ↑ https://www.duolingo.com/comment/2280468$comment_id=4089599
- ↑ "Strengthening a different skill?",https://www.duolingo.com/comment/4579240$comment_id=4591518
- ↑ "Notice some changes in word strength?",https://www.duolingo.com/comment/486819
- ↑ https://www.duolingo.com/comment/2280468$comment_id=4089825
- ↑ http://duolingo.tumblr.com/post/62995947540/a-new-duolingo-for-ios-7
- ↑ https://www.duolingo.com/comment/73926