Writing a situation as an expression before computing it

What to assume they know

The four operations on whole numbers, and the signs +, –, ×, ÷
Reading a two-operand calculation aloud ("five times twenty-five")
Class 6 place value and comfort with three- and four-digit numbers
What it actually takes to make one lakh — reading and writing large numbers, for the later worked amounts

What they should be able to do

Recognise a written arithmetic phrase as an arithmetic expression, and state that it has exactly one value
Use = to link an expression to its value, and read that link as a statement about two names for one number
Read a single expression aloud in more than one way (as an operation, and as a noun such as a sum or a product)
Given a short situation, write an expression describing it before working the number out, and say what part of the situation each piece records
Produce several different expressions with the same value, and explain why that does not make the value ambiguous
Explain what information is lost when an expression is replaced by its value

Where it usually goes wrong

**"= means and the answer is."** It is a claim that both sides name one number, which is why 13 + 4 = ___ + 6 (Part I, §2.1, p.25) is a sensible thing to write at all. A student who reads = as a one-directional command cannot make sense of an expression on the right-hand side.
"Writing 5 × 25 is leaving the job half done." The question asked for the expression. The unevaluated form still shows the daily cost and the number of days; ₹125 shows neither. Both are correct answers to different questions.
"Every number has one proper expression." Twelve is printed with four, and the chapter then asks for more. Many names, one value.
"13 + 2 and 15 are different numbers." They are two names for the same number, in the way that a person's name and nickname pick out one person.
"An expression must contain an operation." A bare numeral names a number too; the chapter's own list of ways to write twelve simply happens to restrict itself to two numbers and one operation, and says so.

Questions to check understanding

Given a short everyday situation, write the expression that describes it (the chapter's own Example 1 shape; recurs throughout §2.2)
Fill a blank so that two expressions have equal value, e.g. 13 + 4 = ___ + 6 (Part I, §2.1, p.25)
Arrange a list of expressions in increasing order of value (Part I, §2.1, p.25)
Write as many expressions as possible for a stated value, with a restriction on how many numbers or which operations may be used — the chapter reopens this at the end of the chapter as a puzzle (Part I, p.45)
Read a given expression aloud in words, and identify which operation it names

Examples worth working on the board

The four opening phrases (Part I, §2.1, p.24): 13 + 2, 20 – 4, 12 × 5, 18 ÷ 3. The chapter works only the first one, stating that 13 + 2 has the value 15 and writing 13 + 2 = 15.
Reading aloud (p.24). The same expression 13 + 2 is offered twice: once as an addition being carried out, once as a noun phrase naming a sum. Both readings are printed.
Example 1 — Mallika (p.24). ₹25 spent on lunch each day, Monday to Friday. The answer the chapter wants is the expression 5 × 25, and it then offers two ways of saying that expression aloud. Note: the chapter does not compute ₹125 here. Leaving it unevaluated is the point of the example.
Twelve, four ways (p.24): 10 + 2, 15 – 3, 3 × 4, 24 ÷ 2. All four use exactly two numbers and one of the four operations. Good raw material for a fan-out visual: one value at the centre, four names around it.
The open task (p.24): choose a number of your own and write as many expressions for it as you can. Worth running live in the explanation with a small number, because it is where a student first feels that the naming is not unique.
Comparison between two expressions (p.24, carried into p.25): the chapter writes 10 + 2 > 7 + 1, which puts a relation sign between two expressions with no numeral in sight. Use it here only to show that =, < and > relate values, and hand the argument on to Comparing two expressions by reasoning, not by evaluating.
No figure is needed for this topic. Printed p.24 was looked at: apart from the chapter banner and a QR code in the top corner, the page carries no diagram, table or number line.

Figures to have open

No textbook figure is required. Printed p.24 (Part I) was inspected; the section carries running text and centred display lines only.
The "one value, many names" fan-out in section 7 is a standard schematic.
The ₹25 × 5 lunch strip in sections 5–6 is also not in the book; the textbook prints no picture with Example 1.

Where this sits in the book

NCERT Ganita Prakash, Class 7, Part I, printed Chapter 2 "Arithmetic Expressions", §2.1 "Simple Expressions" — pp.24–25; the material for this topic sits on p.24, with the comparison signs spilling onto p.25.
Chapter SUMMARY, Part I, p.44 — the first bullet frames §2.1 as a revision of what an expression and its value mean.
Closing puzzle page, Part I, p.45 — reopens "many expressions, one value" as an extended task.
Forward pointer: Part I, printed Chapter 4 "Expressions using Letter-Numbers" (§4.1–§4.2), where the same idea is redone with letters standing in for numbers.