Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 118 · 40 questions

What you do (Heat shows the secret): 1. Dip a cotton bud in lemon juice and write a secret message on white paper. 2. Let the paper dry completely — the writing disappears. 3. An adult irons the paper on a low setting while you watch from a safe distance. 4. Read the brown message and wash your hands.

1. 1.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) reading the message (c) plugging in the iron (d) writing the message
2. 2.🍋 Secret message: who does this step — cutting the lemon? (a) a child can do it (b) an adult does it
3. 3.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we measure it (b) we keep it the same (c) we change it
4. 4.🛟 Who should use the hot iron in the secret message experiment? (a) the youngest child (b) any child (c) only an adult (d) whoever is fastest
5. 5.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is what we measure. (a) False (b) True
6. 6.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) yeast (c) a cotton bud (d) white paper
7. 7.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is kept the same. (a) True (b) False
8. 8.True or false: dipping the cotton bud is a job for an adult. (a) False (b) True
9. 9.🔍 Which is the odd one out? (a) reading the message (b) writing the message (c) dipping the cotton bud (d) cutting the lemon
10. 10.🍋 Which of these steps is a job for an adult? (a) cutting the lemon (b) reading the message (c) dipping the cotton bud (d) writing the message
11. 11.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) lemon juice (c) a small bowl (d) a magnet
12. 12.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) lemon juice (c) a small bowl (d) a balloon
13. 13.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) a small bowl (c) a battery cell (d) an adult with an iron
14. 14.True or false: turmeric powder is not needed for the secret lemon message. (a) False (b) True
15. 15.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is what we measure. (a) False (b) True
16. 16.True or false: a small bowl is not needed for the secret lemon message. (a) False (b) True
17. 17.True or false: reading the message is a job for an adult. (a) False (b) True
18. 18.🧺 Do we need lemon juice for the secret lemon message? (a) not needed (b) needed
19. 19.🔮 Predict: the adult irons for only one second. What happens? (a) writing stays faint (b) writing turns green (c) the paper floats (d) it gets darker
20. 20.📘 The browning of lemon juice with heat is a ___ change. (a) magnetic (b) chemical (c) musical (d) physical
21. 21.🍋 Secret message: who does this step — letting the paper dry? (a) an adult does it (b) a child can do it
22. 22.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we keep it the same (b) we change it (c) we measure it
23. 23.🔍 Which is the odd one out? (a) reading the message (b) cutting the lemon (c) plugging in the iron (d) ironing the paper
24. 24.True or false: yeast is not needed for the secret lemon message. (a) True (b) False
25. 25.True or false: putting the iron away is a job a child can do. (a) True (b) False
26. 26.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) blue words (b) dark brown words (c) almost nothing (d) a rainbow
27. 27.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
28. 28.True or false: a small bowl is needed for the secret lemon message. (a) False (b) True
29. 29.🍋 What colour does the lemon writing turn when an adult warms it? (a) white (b) blue (c) green (d) brown
30. 30.True or false: dipping the cotton bud is a job a child can do. (a) False (b) True
31. 31.🍋 Secret message: who does this step — writing the message? (a) an adult does it (b) a child can do it
32. 32.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is the one thing we change. (a) True (b) False
33. 33.🍋 Why can’t you see the lemon writing once it dries? (a) dry juice is see-through (b) the paper ate it (c) the ink is magnetic (d) it turned into air
34. 34.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is kept the same. (a) True (b) False
35. 35.True or false: an adult with an iron is needed for the secret lemon message. (a) False (b) True
36. 36.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the iron setting (b) how dark the writing is (c) the kind of juice
37. 37.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) how dark the writing is (b) the ironing time (c) the same paper (d) the kind of juice
38. 38.🧺 Do we need a balloon for the secret lemon message? (a) needed (b) not needed
39. 39.True or false: a battery cell is needed for the secret lemon message. (a) True (b) False
40. 40.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) lemon juice (c) a balloon (d) a small bowl

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