How to let students study sth and able to use it. Not only in the model they learn but also in similar models. From my own experience, the biggest barrier is negative transfer or interference during the learning process. When the learning objects are similar in two or more subjects, learners are easy to negative transfer, especially in similar ones. Also, lack of practice is another cause of failure in learning transfer. Learning transfer refers to the ability to transfer from one task to the other tasks. What teachers need to do is asks students to learn the connection behind things. During this process, choosing the appropriate tools are also important. A good tool can help students transfer their knowledge, sometimes it can help with the lack of practice the transfer after learning.