Equations & Expressions Toy Trains!

Teacher Stuff Grade 7 Expressions & Equations 7.EE.3 Solve multi‐step real‐life and mathematical problems posed with positive and negative rational numbers in any form (whole numbers, fractions, and decimals), using tools strategically. Apply properties of operations to calculate with numbers in any form; convert between forms as appropriate, and assess the reasonableness of answers, using mental computation and estimation strategies. Big Idea: Creating an expression or equation from a real life context.

Learning Goal This problem gives you the chance to: find and use a number pattern find an algebraic expression for a number pattern

What do you notice? One Square

Now, what’s changed?

And now what has changed?

Turn to your partner and tell them how many wheels will be in Size 4 set.

How many wheels are in a size 4 set? Justify your answer to your neighbor?

Describe Size 10 of this train set pattern. How many wheels in a Size 10 train set?..... n

Let’s organize our data.

Create a Table Size of Train (n)What I SeeTotal Number of Wheels

The biggest set in the Train Store is Size 12. How many wheels are there in the Size 12 Set?

Nick Your friend, Nick, says his train set has 42 wheels. Can Nick be correct? Convince your partner.

The factory where the trains are made needs a rule for the number of wheels in any size set, so that it can use this in its computer. Write an algebraic expression for the number of wheels in a Size n set.

Exit Slip Explain how your algebraic expression would change if a caboose was added to the end of your train and had 2 wheels on each side.