Intervention and Monitoring Tools

Scales, weights and first degree equations

Class

Reasoning/Algebra

- Engagement/Sustaining efforts and persistence
- Representation/Language and symbols
- Representation/Comprehension
- Action and expression/Physical action

- Engineering classroom discussions
- Providing feedback
- Activating learners as the owners of their own learning

• Scale of plates
• Tokens and weights.
• Paper and pencil.

30 Minutes

1. Consider a balanced scale such that:


In one of the scales' plates there is a weight of 40 grams and in the other plate there are two equal disks.
a) How much does each disc weigh?
Indicate all performed calculations and reasoning.
b) Represent the weight of a disk by y and write a mathematical expression that translates the described situation.

2. Now consider that another 20 grams weight has been added to each of the plates.


a) Will the balance remain balanced?
b) What will the weight of each disc be now?
c) Represent the weight of a disk as z and write a mathematical expression that translates the described situation.
d) What do you conclude about the calculated

With this task it is intended that the student establishes a relationship between an equation and a balanced scale and translates the situation into mathematical language.
It is intended that the student uses letters to represent variables or unknowns and understands the principles of equivalence, describing them and solving equations of
degree 1.

Oliveira, H., A Álgebra no Novo Programa de Matemática do Ensino Básico, Educação e Matemática, 105, 83-86, (2009).

Intervention Tool 2.pdf

Monitoring Tool 2.pdf