## Operations & Algebraic Thinking

** Problem 153: Number Sentence Puzzles -** Students are presented with three number sentences such
as 145 + N = 375, and asked to select which
'spacy' word problem they belong to.
[Grade: 3-4 | Topics: Number Topics and problem solving]

**Problem 149: Equations with One Variable -** Students solve formulas of the form 2001 = 1858 + 11x to find 'X'.
[Grade: 3-5 | Topics: addition, subtraction, multiplication, division; solving simple equations]

**Problem 24: Reading Between the Lines** Students solve simple equations for x, (like 2x + 3
= 5) to discover which words complete an essay on the causes of aurora,
and answer questions after reading the completed essay.
[Grade: 5 - 7 | Topics: solving for X; distributive law; associative law]