These KaBoom cards are a fun way to practice finding the Highest Common Factor (or Greatest Common Factor) and the Lowest Common Multiple (Least Common Multiple) of two or three numbers, with differentiation built in.

Players choose whether they want to choose an easier question (red), but will receive less points for their correct answer, or risk a more challenging question (green) and gain greater rewards. Both a UK version and a US version is included to take into account the specific wording used in each curriculum.

The red cards consist of questions involving simpler HCF and LCM questions that can be worked out by listing the factors and multiples of the given numbers.

The Yellow Cards of questions which require finding prime factors first.

The Green Card consists of more challenging questions involving 3 numbers, or factors of 7 and 13.

Begin by laying all the cards out face down (so you see only the number of points they are worth). Players take turns to select a card, either red, yellow or green. The difficulty of the question will increase. They may also pick up either steal, giving them a chance to steal from any other player, shield, which protects them from the next KaBoom, and KaBoom cards which means you lose all your collected points so far.

Play as a whole class in teams, or print multiple copies as play around the table. If students get the answer incorrect, or they need some help, use your judgement as to whether you will allow them another guess or not. Questions answered incorrectly go in the ‘house’ pile, along with any cards lost in a KaBoom. At the end of the game, add up the ‘house’ pile. The winner is the player or team with the highest points (including any shield cards that have been unused). The house can win.

Included are two copies of the game; one designed for a double sided printer and one designed for single sided printing where you need to turn over the pages yourself to print double sided.

Full instructions are included as are answers.