Estimate the lengths of these lines in centimetres.

Add your estimates together.

Hint: Your classroom door is probably two metres tall. How do the lines compare to that length?

A Mathematics Lesson Starter Of The Day


Topics: Starter | Estimating

  • Marilyn Heath, 182736
  • Brill starter for Y6 lesson on estimates & approximation.
  • Transum,
  • The guess is that in the typical Mathematics lesson there are not as many opportunities for estimation as there should be. Whether it is estimating lengths, angles, weights or time the techniques for arriving at a good answer need to be practised. Do students know that the height of the classroom door is roughly two metres and can they use this as a comparison to estimate other lengths. A 1kg bag of sugar or flour is also a good resource to have in the classroom being a familiar weight to compare other weights with. Estimating answers to mathematical questions before accurately working out the exact answer is a very important check.

    Sorry, there are no answers for this starter because it depends on the size of your projected image. Perhaps when everyone has had chance to make their estimates, some students could come up to the board and measure the actual lengths of the lines.
    Teaching points could include:
    - Appropriate units of measurement to use;
    - Appropriate degree of accuracy
    Of course there is always the issue of correctly adding together the estimated lengths too!"

How did you use this starter? Can you suggest how teachers could present or develop this resource? Do you have any comments? It is always useful to receive feedback and helps make this free resource even more useful for Maths teachers anywhere in the world.
Click here to enter your comments.

If you don't have the time to provide feedback we'd really appreciate it if you could give this page a score! We are constantly improving and adding to these starters so it would be really helpful to know which ones are most useful. Simply click on a button below:

Excellent, I would like to see more like this
Good, achieved the results I required
Didn't really capture the interest of the students
Not for me! I wouldn't use this type of activity.

This starter has scored a mean of 3.1 out of 5 based on 176 votes.

Previous Day | This starter is for 2 September | Next Day


The answer will vary depending on how large your projector image is. Use a tape measure or ruler to measure the lines then add the results together. Who in the class got closest to the sum of your measurements?

Note to teacher: Doing this activity once with a class helps students develop strategies. It is only when they do this activity a second time that they will have the opportunity to practise those strategies. That is when the learning is consolidated. Click the button above to regenerate another version of this starter from random numbers.

Teaching idea: Allow the pupils to work on this activity without any help. Once they have arrived at an answer, collect ideas from the class about strategies used then give the pupils a chance to re-estimate the lengths. As a point of reference, the classroom door is probably around 2m tall. Use a large ruler to find the correct lengths but stress that getting the answer exactly right was not expected.

Presentation Tip: Press the F11 key (except on MS Edge) to hide the tool bars if the lines don't fit on to your screen. You can also use the zoom option in your browser's menu to vary the display size.

Your access to the majority of the Transum resources continues to be free but you can help support the continued growth of the website by doing your Amazon shopping using the links on this page. Below is an Amazon search box and some items chosen and recommended by Transum Mathematics to get you started.

Have you read Craig's book yet?

Craig Barton must surely be the voice of Mathematics teachers in the UK. His wonderful podcasts interviewing the industry experts have culminated in this wonderful book. As Craig says: "I genuinely believe I have never taught mathematics better, and my students have never learned more. I just wish I had known all of this twelve years ago..." more...

"How I wish I'd taught Maths" is an extraordinary and important book. Part guide to research, part memoir, part survival handbook, it’s a wonderfully accessible guide to the latest research on teaching mathematics, presented in a disarmingly honest and readable way. I know of no other book that presents as much usable research evidence on the dos and don’ts of mathematics teaching in such a clear and practical way. No matter how long you have been doing it, if you teach mathematics—from primary school to university—this book is for you." Dylan Wiliam, Emeritus Professor of Educational Assessment, UCL.

The Craig Barton Book

Casio Classwiz Calculator

There is currently a lot of talk about this new calculator being the best in its price range for use in the Maths classroom. The new ClassWiz features a high-resolution display making it easier to view numerical formulas and symbols but it isn't a graphical calculator as such (it has the capacity to draw graphs on your smart phone or tablet, via a scannable QR code and an app).

As well as basic spreadsheet mode and an equation solving feature you also get the ability to solve quadratic, cubic or quartic polynomial inequalities and the answer is given just as it should be written down, using the correct inequality symbols!

This calculator has a high-performance processor and twice the memory of previous models ensuring speedy operation and superior computational power.more...

Online Maths Shop

Laptops In Lessons

Teacher, do your students have access to computers?
Do they have iPads or Laptops in Lessons?

Whether your students each have a TabletPC, a Surface or a Mac, this activity lends itself to eLearning (Engaged Learning).

Laptops In Lessons

Here a concise URL for a version of this page without the comments.

Here is the URL which will take them to a related student activity.

Student Activity


Extension Activity

How many tins of paint are required to paint the Dome Café? Make some assumptions, do some research then estimate.

Dome Cafe

©1997-2019 WWW.TRANSUM.ORG