Note down your most important takeaways

Give everyone a pen and sticky note (or a link to a shared editable document) and ask them to note down an answer to a question like this (pick the question you find most appropriate).

Encourage them to take the note with them and stick it on their desk, (or take a screenshot of the document and keep it on their computer desktop) for a week.

Benefits

The idea is to help them remember the most important things they learnt. The learning is reinforced by putting it into their own words, and placing it somewhere they will read it again during the week.