Asking the Experts

Ok, my students are really struggling with mixed numbers and improper fractions. So I'm asking the experts--you guys! I'm working with LOW 4th graders and they've been doing pretty well with understanding fractions, but this is really stumping them. We've worked with pattern blocks, fraction bars, and real-life situations. They can understand that numbers like this exist, but they as soon as they see a picture of 2 whole circles and half of another, they label it 5/6. Does anyone have any good manipulatives or lessons that would help with this?

Lesson to Share

Topic-Area and Perimeter
Grade Level-I did with 4th but I think it work for 3rd and 5th too.
Objective-See the difference between area and perimeter and be able to construct rectangles with a given area or perimeter.

My students respond well when there is food involved in a lesson. They pay more attention and behave well because I don't let them eat the food unless they do well. So I used Cheez-its to help students see the square units involved in area. We began by making rectangles of certain dimensions and finding the area and perimeter. This helped them to see how we count inside squares for area and edges for perimeter. I then gave the students a given area and had them construct their own rectangles. We then shared the dimensions of our rectangles and students could see how different perimeters had the same area, and vice versa because I then gave them a perimeter to construct.
This activity really helped my students understand why area is written with square units and perimeter is just regular units. They were also able to see how why we multiply L x W to find area, because they naturally did that when counting their Cheez-its.