Invisible Ink Experiment Worksheet

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

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