We used babble for our example call tool. The type of feedback it provided was how either I was wrong or right in a sentence, duo lingo gave the correct solution after failing, and why. duo lingo seems to be better in this sense as it helps you actually learn instead of telling you if you’re right or wrong. It did not allow us to include a cloze into the answer. The tool allowed to work on a language, or through, meaning you are allowed to start at a different place.