This video explains what triangular numbers are and the patterns associated with them. Two puzzles are at the end of the video. Skip to: 00:00 Introduction 00:22 What exactly is a triangular number? 00:42 What patterns do you notice about the sequence? 01:43 How to find a triangular number 02:20 Practice questions/ puzzles

This short video shows you a quick trick which can be used for some mental multiplication questions. Looking at the whole question first, without initially working from left to right, can help reduce the load on short-term memory when doing mental arithmetic. Practice questions at the end of the video. Note this tip only works with certain problems but working this way encourages you to assess the question first and become more flexible when working with numbers.

This video explains what area is and how to calculate the area of a rectangle or square. The video uses a reversed task style of teaching. Practice questions are at the end of the video.

This video explains what a reciprocal of a whole number is and what a reciprocal of a reciprocal is. Practice questions at the end of the video.

Square Roots Explained: what exactly is a square root? Practice questions at the end of the video.

This video provides five shape puzzles, designed to develop problem solving and algebraic skills. The following videos may help: Using algebra to find the missing value: https://youtu.be/fxoF6aGYTpk BODMAS: https://youtu.be/nLQLBr4DSj8

This video explains how to partition numbers. This is an extremely important skill for both children and adults to have. It can greatly assist with mental arithmetic and being able to manipulate numbers. We cover addition and subtraction using partitioning. Practice questions are at the end of the video.

How Many Squares Are On A Chessboard? The answer is not 64! This puzzle will help you develop your problem solving skills. The answer is given at the end of the video but make sure to try work it out yourself first.

This video explains what cube numbers are, what it means to cube a number and provides a range of practice questions and answers at the end of the video.

This video explains what square numbers are and provides practice questions and answers.

This video covers how to multiply out/expand single brackets, including brackets with powers and negative multipliers . Practice questions are at the end of the video.

This video explains how to solve number riddles. 8 riddles of varying difficulty (and with answers) are provided for you to complete. Activities like this help to promote number sense and problem solving skills.

This video shows you how to find the volume of a frustum and explains what a frustum is. We also explain how to find the radius of the smaller/removed cone. There are two practice questions at the end of the video.

This video explains lines of symmetry of 2D shapes including triangles, quadrilaterals and regular polygons. Practice questions are at the end of the video.

This video explains what pentominoes are and provides four pentominoes puzzles and solutions. A great activity to develop your problem solving skills!

This video explains how to draw 2D projections of 3D shapes: plans, front elevations and side elevations. Practice questions are at the end of the video.

This video explains two methods to find the highest common factor (also known as the greatest common factor) of two or more numbers: by listing the factors or by prime factorisation. For a refresher on multiples and factors: https://youtu.be/4EkhaETrcnY For a refresher on prime factors: https://youtu.be/1zagn5okZgM

In this video we show you how to draw 3D shapes on isometric paper. There are practice questions at the end of the video. You can download some isometric paper from here: https://nrich.maths.org/isometricpaper

We explain how to find the lowest common multiple of two or more numbers, using two methods: listing the multiples and using prime factorisation. Practice questions and answers are at the end of the video.

This video explains how to find the prime factors of a number using the factor tree method. Practice questions are at the end of the video.