BASIC: Simple Statements and Programs

Lesson objectives

By the end of the week, learners should be able to:

1. Write a LET, PRINT and arithmetic combination in one program.
2. Assign a score to a variable and display a calculated total.
3. Use two arithmetic operators inside one LET.
4. Interpret a printed number with a PRINT# or PRINT command.
5. Compare two programs that differ only in operators.

Key vocabulary

• Arithmetic operator: plus, minus, multiply or divide in an expression.
• Expression: a combination of values and operators evaluated to a result.
• Calculation: a LET statement performing an arithmetic operation.
• Display: showing the result of an expression on the screen.
• Comparison: checking whether two expressions are equal or not equal.
• Equality operator: a symbol such as equals or not equals in an expression.

Common misconceptions

• "Operators always come after values." Multiplication and division sit between operands in the expression.
• "PRINT prints the expression itself." PRINT displays the evaluated result, not the expression text.
• "Higher precedence always means more lines of code." Higher precedence changes grouping, not code length.

Teacher activities

1. Starter: display two LET statements differing only in operator and ask which changes the result.
2. Model combining LET, PRINT and arithmetic in one program.
3. Demonstrate assigning a score and computing a total with two operators.
4. Show two PRINT commands displaying the difference between the expression and its result.
5. Give learners three LET variations to predict the output.
6. Close with the comparison question and exit question about precedence.

Student activities

1. Observe the starter variation and predict which changes the result.
2. Write a LET, PRINT and arithmetic combination in one program.
3. Assign a score and display a calculated total using two operators.
4. Interpret the printed result against the predicted expression value.
5. Predict the output of three LET variations.
6. Answer the exit question in one sentence about expression precedence.

Practical / learning evidence

Three BASIC programs differing in operator choice, each with documented expected output. Submit all three programs and outputs for marking.

Resources and preparation

Computers with the interpreter, blank source windows and a sample-input sheet. Preload the interpreter with the base Welcome prompt so learners start clean. Disable Caps Lock before typing.

Assessment for learning

Inspect each program for correct LET and PRINT syntax. Verify each output matches the predicted value. Flag any learner who thinks PRINT prints the expression text.

Inclusion and homework

Prebuild the interpreter folder with Welcome and sample programs for learners lacking install capability. Provide the sample-input sheet with output answers hidden until marked. Extend confident learners with a LET that assigns a percentage calculation.