This ActivInspire flipchart is a fun way for students to practice addition, subtraction, multiplication, or division. The teacher sets up in advance as many slides as she wants for practicing computation. Students can make estimates on whiteboards at their desks, solve the problem, then check their answers against their estimates for reasonableness. The teacher and/or student helper can use the "Magic Ruler" to reveal correct answers on the Promethean board. This flipchart is completely adaptable for many grade levels and abilities. I created it for subtraction with regrouping, but the teacher can easily change the title to any of the other operations. Instructions for editing can be found in the notes section of the third slide.