Learning goal
Students place tenths between whole numbers and explain why a digit’s position matters. This short activity uses a drawn number line and decimal cards; it does not require money examples or prior work with hundredths. Learners should connect the written decimal to equal intervals, not treat the digits after the point as a separate whole number.
Prepare the line
Draw a line from 0 to 1. Mark both endpoints, then divide the distance into ten equal intervals. Label the marks 0.0, 0.1, 0.2 and so on through 1.0. Ask learners to check that there are ten spaces, not ten marks between the endpoints. Extend the same scale from 1 to 2 if students need another whole-number interval.
Place and explain
Give pairs the cards 0.3, 0.7, 1.2 and 1.8. Ask them to place each card and explain its location using the words whole and tenth. For example, 1.2 is one whole and two tenths, so it belongs two equal steps after 1. Use the same interval size throughout. Invite a partner to verify the step count before moving to the next card.
Compare without reading digits as a whole number
Ask which is greater, 0.4 or 0.6, and require learners to point to both locations. Then compare 1.3 and 1.7. Students should explain that both are within the same whole-number interval and that seven tenths lies farther to the right than three tenths. Ask why 0.8 is less than 1 even though 8 is a large whole number; the number line makes the unit explicit.
Use a deliberate error
Show a learner statement: “1.4 is less than 1.2 because four is less than two after the decimal point.” Ask the class to test it on the line. The marks show that 1.4 lies to the right of 1.2, so it is greater. Emphasise that the comparison works here because both values have one digit in the tenths place. Do not generalise the shortcut to decimals with different place lengths without teaching equivalent notation.
Support and extend
For support, provide a line already split into ten equal intervals and let learners place only 0.2, 0.5 and 0.9. Ask them to count hops aloud. For extension, place 1.5 and ask for a value halfway between 1.4 and 1.6; accept 1.5 with an explanation tied to the equal spacing. Students ready for hundredths can first estimate a location, then refine the interval with a new scale rather than squeezing extra marks into the tenths line.
Exit check
Ask each learner to mark 0.6 on a blank 0-to-1 line and complete: “I placed it ___ tenths after zero because ___.” Expected response: six equal intervals after zero. A second prompt asks whether 1.6 is greater than 1.4 and why. Use the explanation to see whether the learner connects the whole-number part, equal intervals and direction on the line. If marks are uneven, ask for an estimate and discuss the model before grading precision.
Teacher resource prepared for Schoolizer. The paper-folding cover image is decorative; the activity uses a number line.
