Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 650 · 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 is not needed for the secret lemon message? (a) white paper (b) a cotton bud (c) a battery cell (d) a small bowl
2. 2.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) white paper (c) a mirror (d) lemon juice
3. 3.🔍 Which is the odd one out? (a) ironing the paper (b) reading the message (c) writing the message (d) dipping the cotton bud
4. 4.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) how dark the writing is (b) the kind of juice (c) the iron setting (d) the same paper
5. 5.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a balloon (b) white paper (c) a small bowl (d) a cotton bud
6. 6.True or false: plugging in the iron is a job for an adult. (a) False (b) True
7. 7.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the kind of juice (b) the same paper (c) how dark the writing is
8. 8.🛟 Why must children keep their fingers away from the iron? (a) it is sticky (b) it can burn skin (c) it is magnetic (d) it is cold
9. 9.🧺 Do we need a cotton bud for the secret lemon message? (a) not needed (b) needed
10. 10.True or false: putting the iron away is a job for an adult. (a) False (b) True
11. 11.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) a battery cell (c) a cotton bud (d) lemon juice
12. 12.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) lemon juice (c) white paper (d) yeast
13. 13.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) dark brown words (b) blue words (c) a rainbow (d) almost nothing
14. 14.🍋 Secret message: who does this step — cutting the lemon? (a) an adult does it (b) a child can do it
15. 15.True or false: dipping the cotton bud is a job for an adult. (a) False (b) True
16. 16.🧺 Which of these is not needed for the secret lemon message? (a) yeast (b) a cotton bud (c) a small bowl (d) white paper
17. 17.🍋 Why can’t you see the lemon writing once it dries? (a) the ink is magnetic (b) it turned into air (c) the paper ate it (d) dry juice is see-through
18. 18.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) a cotton bud (c) lemon juice (d) a magnet
19. 19.📘 The browning of lemon juice with heat is a ___ change. (a) musical (b) physical (c) magnetic (d) chemical
20. 20.True or false: turmeric powder is not needed for the secret lemon message. (a) False (b) True
21. 21.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) white paper (c) lemon juice (d) a magnet
22. 22.True or false: a cotton bud is not needed for the secret lemon message. (a) False (b) True
23. 23.⚖️ 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) True (b) False
24. 24.🧺 Do we need a balloon for the secret lemon message? (a) not needed (b) needed
25. 25.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) a mirror (c) a small bowl (d) an adult with an iron
26. 26.True or false: white paper is needed for the secret lemon message. (a) False (b) True
27. 27.🔮 Predict: the adult irons for only one second. What happens? (a) writing turns green (b) it gets darker (c) writing stays faint (d) the paper floats
28. 28.⚖️ 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
29. 29.🍋 Which of these steps is a job for an adult? (a) reading the message (b) letting the paper dry (c) dipping the cotton bud (d) ironing the paper
30. 30.True or false: letting the paper dry is a job a child can do. (a) True (b) False
31. 31.True or false: plugging in the iron is a job a child can do. (a) True (b) False
32. 32.🍋 What colour does the lemon writing turn when an adult warms it? (a) blue (b) green (c) white (d) brown
33. 33.🔍 Which is the odd one out? (a) putting the iron away (b) writing the message (c) dipping the cotton bud (d) letting the paper dry
34. 34.🔮 Can the brown writing go back to being invisible? (a) yes, if shaken (b) yes, in the dark (c) yes, if cooled (d) no, it stays brown
35. 35.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is the one thing we change. (a) False (b) True
36. 36.True or false: a balloon is needed for the secret lemon message. (a) False (b) True
37. 37.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) rub your eyes (b) skip washing (c) wash your hands (d) lick your fingers
38. 38.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) dipping the cotton bud (c) ironing the paper (d) plugging in the iron
39. 39.🍋 Secret message: who does this step — dipping the cotton bud? (a) an adult does it (b) a child can do it
40. 40.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is the one thing we change. (a) True (b) False

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