Interleaving is a learning technique discussed in "Make It Stick" that involves mixing different topics or forms of practice, in contrast to focusing on one skill or topic at a time, known as blocking. When you interleave your study, you weave in and out of several topics in your practice sessions. This approach forces your brain to constantly retrieve different kinds of information and adapt to solve different types of problems. The effort involved in this switching process helps to create deeper learning and better transfer of knowledge and skills to new contexts.

Interleaving works well for several reasons:

• It strengthens memory associations since the learner must discern how different types of problems (or topics) require different strategies.
• It improves problem-solving skills by teaching the brain to apply knowledge flexibly and in varied contexts.
• It prevents the feeling of fluency that comes with blocked practice (where one can be deceived into thinking they have mastered something simply because they can do it repeatedly in the short term).

Examples within the Context of Second Language Acquisition:

1. Vocabulary Building: Instead of studying vocabulary thematically (e.g., all fruits one day, all colors the next), an interleaved practice would mix up different categories of words. So, in one study session, a learner might study a mix of fruits, colors, and clothing. This approach can help in better retention and recall.

2. Grammar Drills: Rather than practicing only one tense or grammatical structure at a time, interleaving would involve practicing various tenses and structures within a single study session. This might mean switching between present, past, and future tenses, or combining exercises on adjective-noun agreement with verb conjugation exercises.

3. Skill Practice: In language learning, you have the four key skills: reading, writing, listening, and speaking. An interleaved practice routine might involve reading a text, then listening to an audio recording, followed by writing a response, and finishing with speaking practice. This method helps a learner become more adaptable in using the language across different contexts.

4. Cultural Lessons: If a learner is studying the cultural aspects of a language, they could interleave learning about history, music, cuisine, and literature in a single session, rather than focusing on just one cultural aspect at a time. This approach can lead to a more nuanced understanding of the language's cultural context.

5. Type of Texts: Instead of reading several short stories back-to-back, a learner might read a short story, then a newspaper article, followed by a poem, which can improve comprehension and the ability to switch between different styles and registers of language.

6. Language Skills: In the context of practicing language production, a learner could switch between different types of speaking exercises—such as monologues, dialogues, descriptions, and narrations—in a single practice session.

Interleaving is most effective when you've already had some initial practice or familiarity with the topics you are interweaving. It can feel more challenging than blocked practice because it involves a constant state of learning and adjustment, but this difficulty is part of what makes it so effective for long-term retention and skill development. For language learners, this means that they can adapt more readily to the unpredictability of real-life language use.