One of my students' favorite science topics is mixtures and solutions.
I don't know if it's because the unit is very hands-on and we make chemical reactions occur (often with a loud noise or foaming bubbles). Maybe it's because mixtures and solutions is kind of like potions and they wish they were at Hogwarts (that would be my dream).
Since supplies are limited and we can't necessarily have a chemical reaction a day, I created a sort for mixtures and solutions, available here.
I would go over the difference between mixtures and solutions, then allow students to complete this sort as a table team. While they were discussing, I would walk around listening and doing an informal assessment. Students would then walk around and critique one another's work in a gallery walk format. They're allowed to look and discuss why they agree or disagree, but they can't touch one another's work. After they've gotten a chance to observe the other tables, they return to their seats and we go over just a few of the answers. They discuss why a particular combination is either a mixture or a solution.
We repeat this activity several times throughout the unit and again before testing.
Hope your students enjoy it as much as mine do!