# Dot chain sequences

## Lesson details

### Key learning points

1. In this lesson, we will learn how to group dot chains and generalise to find n-chains. We formulate calculations that represent dot chains.

### Licence

This content is made available by Oak National Academy Limited and its partners and licensed under Oak’s terms & conditions (Collection 1), except where otherwise stated.

## Video

Share with pupils

## Worksheet

Share with pupils

## Starter quiz

Share with pupils

### 5 Questions

Q1.
What do we mean if we describe a sequence as "descending"?
The sequence is all negative numbers
Correct answer: The sequence is decreasing term-to-term
The sequence is less important
Q2.
Which of the following is an example of a descending sequence?
-12, -10, -8, -6, ...
-5, -4, -3, -2, ...
Correct answer: 10, 8, 6, 4, ...
3, 4, 5, 6, ...
Q3.
What is the nth term of 10, 8, 6, 4, 2, ...?
-2n + 8
2n + 12
2n + 8
Q4.
What is the nth term of -4, -7, -10, -13, ...?
-3n + 1
-4n + 7
3n - 7
Q5.
Find the first 5 terms of the sequence -5n + 2.
Correct answer: -3, -8, -13, -18, -23
-5, -3, -1, 1, 3
-5, 2, 9, 18, 27
-7, -12, -17, -22, -27

## Exit quiz

Share with pupils

### 5 Questions

Q1.
What is the tracking calculation for the grouping of this 3-chain?
27
8 + 8 + 1
Correct answer: 8 x 3 + 1
9 x 3 + 1
Q2.
If the tracking calculation for this 3-chain is 8 x 3 + 1, what would the tracking calculation for a 20-chain?
20 x 3 + 1
Correct answer: 8 x 20 + 1
8 x 3 + 20
Q3.
What is the tracking calculation for the grouping of this 3-chain?
3 x 6 + 3 +1
Correct answer: 3 x 7 + 3 + 1
3 x 7 + 4
3 x 8 + 3 + 1
Q4.
If the tracking calculation for this 3-chain is 3 x 7 + 3 + 1, what would be the tracking calculation for an 100-chain?
100 x 7 + 100 + 1
Correct answer: 100 x 7 + 3 + 1
100 x 7 + 4
3 x 100 + 100 + 1
Q5.
Using the grouping of this 3-chain, what is the tracking calculation for an n-chain? Write you answer as an algebraic expression.
3n + 1
3n + 8