Sometimes you just need to start with a visual to have the students find a math question. Here is a great website that gives a picture, and then you can have students brainstorm what the math question might be! http://www.101qs.com/
This Illuminations website allows you to create papers that include items like: grids, shapes, nets, number lines, graph paper, spinners, etc...... You can then download it as a PDF or a JPG to insert into other documents.
Website
Website
This website has many different Virtual Manipulatives Grades K-8, sorted by Common Core Domain.
Website
Website