# Dora to the Rescue

Next on Making Algebra Meaningful  – Dora to the Rescue!

Our goal is to tackle this beast from our expectations:

add and subtract polynomials involving the same variable up to degree three [e.g., (2x + 1) + (x^2 – 3x + 4)],using a variety of tools

and

multiply a polynomial by a monomial involving the same variable to give results up to degree three [e.g., (2x)(3x), 2x(x + 3)], using a variety of tools

#### Part 1 (Act 1) Being Curious

Give students time to decide first if it was still possible and second how could we do it?
They’ll want me to go get another tape measure. But we won’t have one….they’re all broken!!…what could we do? I’m looking for them to say “let’s use “some object” to measure the dimensions” — Dora to the Rescue!

#### Act 2 – Still being curious We guessed at how many Dora’s would fit the length Reveal:

Guess at how many Dora’s would fit the width

Reveal:

#### Part 2: The Struggle (Collaboration)

At this part students will want to know Dora’s height.

Let them work on finding the perimeter and then the area of the countertop.

#### Part 3: Connect

We can share solutions and this is my part to ask about how efficient their strategy is. Introduce finding an expression for perimeter in terms of Dora first using slides like this:

Introduce finding an algebraic expression for area and use it to find the area of the countertop.

Part 4: Consolidate

Updated: Oct. 13 2015

Consolidate with Knowledgehook’s Gameshow. Play this custom gameshow to extend your students thinking on making algebraic expressions.

Or use a paper version to consolidate:

Let’s take our new skills on collecting like terms and the distributive property and practice them. We’ll practice with @mathletepearce’s Rake problem.