SecondaryMaths

# 10 of the best KS3 maths resources for Lowest Common Multiple (LCM) and Highest Common Factor (HCF)

Give your class a firm foundation in factors, multiples and prime numbers with these excellent ideas…

by Teachwire
SecondaryMaths

Lowest common multiple (LCM), also known as least common multiple, and highest common factor (HCF), also known as greatest common factor can get confusing for students, and that’s just in getting the names right.

That’s why we’ve rounded up these great resources, guides, activities and lesson plans to help you help pupils get to grips with this part of the maths curriculum.

## 1 | Fruit Splat

This simple game is a gentle introduction to lowest common multiples, with three difficulty settings and multiple-choice answers to help students get to grips with the concept.

You can play it here.

## 2 | Prime factorisation approach

In this video you can practise finding the least common multiple in some example exercises, and it’ll teach you the prime factorisation approach to finding the lowest common multiple)

Find this video and more on the Khan Academy site, here.

## 3 | Factor trees

If students need a quick practice on factor trees then this site features a handful of increasingly challenging questions for them.

They just need to type whole numbers (greater than one) into the circles, which when multiplied together give the number in the circle above them.

Each branch of the tree will eventually end in a prime number.

Try it out here.

## 4 | Christmas bells

This festive starter activity has the added bonus of putting lowest common multiple problems into a real world perspective.

It poses: if three bells ring together at noon, and bell one rings every six minutes, bell two every seven minutes, and bell three every hour, when will they all ring together again?

Find this resource here.

## 5 | Venn diagram worksheet

This resource uses prime numbers and Venn diagrams to find the highest common factor and the lowest common multiple of pairs of numbers.

## 6 | The what factor

The ideas of highest common factor and lowest common multiple are often taught separately, says Colin Foster, but dealing with them together can help learners to appreciate the connections between them.

This is a KS4 lesson plan but can be adapted to use the same principle in KS3.

## 7 | HCF tips and tricks

On to highest common factor, and Jo Morgan’s excellent resourceaholic site has this absolutely jam-packed tips and tricks page on how to teach this part of the maths curriculum.

Check it out here.

## 8 | Higher or lower?

Talking of great maths blogs, Don Steward has some excellent teasers for LCM and HCF.

You can find them here.

## 9 | HCF and LCM worksheet

Want a quick-and-easy printable worksheet to offer your class?

Here’s one.

## 10 | NRICH problems

And finally, here are the NRICH pages that offer all sorts of excellent questions and activities for highest common factor and lowest common multiple.

It has shorter problems to tackle here.

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