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Teacher-led from the board. Pupils do not need a device, but can follow on one.

What you need:
IWB/Projector/Large Screen

Predict Next Year's School Enrolment

Forecast next year's school enrolment using three different methods, mean, year-to-year change, and what-if scenarios, then judge which prediction you trust most.

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1 Getting Started
2 Watch and Notice
3 Try It Together
4 Class Challenge
5 Write Your Best Prediction in Your Journal
6 Think About It
7 What Did We Notice?
8 What's Next
Pupil practice

Your turn

Your teacher is running this lesson on the board. Here is the part you can try yourself.

Your written work is on page 118

Bar chart builder

1 - Getting Started ~4 mins

Illustration for Getting Started Here are our school's enrolment numbers for the last five years:

210, 216, 220, 226, 230

What do you think next year's number will be? Have a good guess before we work anything out.

👇 Mark your steps as done as you complete them.

+5 XP

2 - Watch and Notice ~10 mins

Look at the five past years of enrolment on the chart. We will calculate the mean together, then look at where the dashed mean line sits compared with the last bar. After that we will find three different ways to predict next year, and you will see the prediction bars added on the end of a second chart.

👇 Mark your steps as done as you complete them.

+10 XP

3 - Try It Together ~7 mins

Here are our five years on the chart again: 210, 216, 220, 226, 230. Now we place a sixth bar for next year.

Key point

Before anyone taps, we all say which method is being used: the mean line, the year-to-year step, or a what-if (the trend, then adjusted).

Add the sixth bar: your prediction

+15 XP

4 - Class Challenge ~9 mins

Now use the three methods on real schools' numbers, working in your copy, one method per line.

Core, do this one in full

Ballybane N.S. (Galway): 180, 188, 196, 204, 212. Predict next year using (1) the mean, (2) the year-to-year step, and (3) a what-if: what if 20 pupils leave for a new school nearby?

Then this comparison:

Douglas N.S. (Cork): 300, 298, 302, 296, 300. These numbers wobble up and down. Find the mean, then say whether the year-to-year step suits this school or misleads you.

Stretch (if you finish early): for either school, write which one prediction you would put on the school newsletter, and why.

Use three prediction methods on a real school's five-year enrolment figures, then judge which prediction you would trust enough to publish.

Ballybane N.S. (Galway): 180, 188, 196, 204, 212. Predict next year using the MEAN of the five years.
Ballybane N.S.: predict next year using the YEAR-TO-YEAR STEP.
Ballybane N.S.: what if 20 pupils leave for a new school? Predict from the trend, then take 20 off.
Douglas N.S. (Cork): 300, 298, 302, 296, 300. Predict next year using the MEAN, and say whether the step method suits this school.

Ways to start:

Start by adding the five years to find the mean.
Read the jump from each year to the next, is it steady or does it wobble?

Stretch:

For the school you chose, which single prediction would you put on the school newsletter, and why?

Answers & strategies (teacher)

Ballybane N.S. (Galway): 180, 188, 196, 204, 212. Predict next year using the MEAN of the five years. — Mean = 980 ÷ 5 = 196
Ballybane N.S.: predict next year using the YEAR-TO-YEAR STEP. — Each year rises by +8, so 212 + 8 = 220
Ballybane N.S.: what if 20 pupils leave for a new school? Predict from the trend, then take 20 off. — Trend gives 220; 220 − 20 = 200
Douglas N.S. (Cork): 300, 298, 302, 296, 300. Predict next year using the MEAN, and say whether the step method suits this school. — Mean = 1,496 ÷ 5 = 299.2 ≈ 300. The step method does not suit it, the jumps flip up and down, so there is no steady trend.

+15 XP

Pupil practice

Module 9 · Mathematical Modeling and End-of-year Review Mixed

Lesson 126 · Predict Next Year's School Enrolment

Download Activity Book page (PDF)

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