This site specifically evaluates the student's knowledge of the travels of Marco Polo. It would be an excellent conclusion to a lesson on Marco polo since it is visually stimulating, asks questions, and gives immediate feedback.
This site lies out a few historical cases in an entertaining "investigation" format. This can be used by teachers to create an assignment as well as by students to do the research.
The site's mathematical tools are conveniently divided by grade level. With some direction from the teacher, the tools can be used by the students to better understand many math concepts.
This site provides challenging logic problems. They could be given to students during down time to do either in groups or independently.
This is an excellent resource for teachers. It allows teachers to make puzzles that can be used in class to reinforce the days lessons in a stimulating way.
This site shows movies about many different subjects. These movies can be shown in class to add to whatever the students are learning at that time.
This site recommends books for children based on age, reading ability, and general interests. This site would be wonderful to recommend to parents during the summer.
This grammar site is divided by grade level. With some direction, it provides an entertaining way for students to practice their grammar skills.