There are 28 Defuse The Bomb worksheets here, each with answers. These are designed to allow students to get on if confident enough to do so with the answers appearing on the sheet enabling the teacher to help those who require it. These have worked well with online lessons. Topics include algebraic fractions, area and perimeter, transformations, HCF/LCM, related calculations, simultaneous equations and surds. Each of these is available for free individually.