How many bricks? Practising visual estimation

July 24, 2018

Take a cup, pour some Lego® bricks and try to estimate how many there are. Such a simple activity yet such an valuable skill.

Many students (and adults) do not give importance to estimation. It’s a part of mathematics which is often overlooked, as its value is not fully understood. We concentrate on getting the exact result, not knowing why we should learn how to estimate it first.

estimating with lego

However, being able to assess is one of the essential mathematical skills. It helps us in our everyday life. Also, high estimation skills are also one of the characteristics of successful project managers and business leaders. Thanks to estimations we can save money, time and much frustration.

Very often knowing more or less is enough to decide. Not always we need a precise result.

  • Are my calculations correct or am I getting one zero too much/too little?
  • Is it cheaper to buy in bulk or not?
  • How much paint do I need to paint the living room?
  • How many people are before me in the queue? How long will I wait for my turn?
  • How much food should I buy for the barbecue?
  • How much time will it take me to get there?
  • How much will our holidays cost?
  • How many oranges will we need to prepare juice for the whole family?
  • Am I still within the budget?

We can compare the process of estimating the result to sketching our way towards it. After all, it is so much easier to get somewhere once you know where you’re heading. When estimating, we concentrate on a problem and the data, our reasoning goes deeper hence our results are better.

The good news is, one can improve estimation skills by merely practicing them.

So today I would like to share with you some ideas to practice visual estimation using Lego® bricks:

How many bricks?

#1 – spatial estimation

We will need a baseplate (or an even background) and several 2×2 bricks. At first, I use only one color, but as the child gets better at the task, I introduce different colors.

estimating with lego
estimating with lego

#2 – volume estimation

We will need a cup or other container and some bricks. We can use either the 2×2 or the 2×4 ones. We pour some bricks into the cup and try to estimate how many bricks are inside.

estimating with lego

How many Minifigures?

It’s a variation of the first activity, but we use Minifigures instead of bricks. We can place them on a baseplate, but I try to prepare different scenes. They are more challenging than an empty baseplate as there are more distractions.

#1 Baseplate - How many Minifigures are on the street?

estimating with lego

#2 “At the bakery” – How many Minifigures stand in the queue?

We play it several times in a row. I put the Minifigures closer to or further from each other. A child has to work out her strategies on how to deal with the estimation. Although it is easy with up to 10 Minifigures, it gets quite tricky when there are (many) more.

lego at the bakery #1
lego at the bakery #2
lego at the bakery #3

#3 “In the park” – How many Minifigures are in the park?

This version is even more difficult than the Bakery. Minifigures are not standing in a line, but are unevenly spread around the scene. There are also more distractions which make estimation process more challenging.

lego in the park

How many studs long?

Many times, in our Lego-based activities, we use studs as a measuring unit. Here children have to estimate how long is the distance between two objects and say it in studs. In the easy version, we provide a line made of bricks (1 stud wide). In the more difficult one, we can challenge the child to estimate the distance without the help of the bricks. Later on, we can also try estimating the distance in centimeters.

lego in the park
lego in the park
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