Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 484 · 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.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) almost nothing (b) a rainbow (c) dark brown words (d) blue words
2. 2.🧺 Do we need a small bowl for the secret lemon message? (a) not needed (b) needed
3. 3.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) wash your hands (b) lick your fingers (c) rub your eyes (d) skip washing
4. 4.True or false: plugging in the iron is a job for an adult. (a) False (b) True
5. 5.True or false: a battery cell is not needed for the secret lemon message. (a) True (b) False
6. 6.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) how dark the writing is (b) the iron setting (c) the kind of juice
7. 7.🛟 Who should use the hot iron in the secret message experiment? (a) only an adult (b) the youngest child (c) any child (d) whoever is fastest
8. 8.🧺 Do we need a mirror for the secret lemon message? (a) not needed (b) needed
9. 9.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) dipping the cotton bud (c) plugging in the iron (d) reading the message
10. 10.🔍 Which is the odd one out? (a) dipping the cotton bud (b) plugging in the iron (c) cutting the lemon (d) putting the iron away
11. 11.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) turmeric powder (c) an adult with an iron (d) lemon juice
12. 12.🧺 Do we need turmeric powder for the secret lemon message? (a) not needed (b) needed
13. 13.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a balloon (c) a cotton bud (d) an adult with an iron
14. 14.🔍 Which is the odd one out? (a) ironing the paper (b) letting the paper dry (c) reading the message (d) writing the message
15. 15.🍋 Secret message: who does this step — letting the paper dry? (a) a child can do it (b) an adult does it
16. 16.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) a magnet (c) white paper (d) yeast
17. 17.True or false: reading the message is a job for an adult. (a) False (b) True
18. 18.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) letting the paper dry (c) ironing the paper (d) plugging in the iron
19. 19.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we keep it the same (b) we measure it (c) we change it
20. 20.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the same paper (b) the kind of juice (c) how dark the writing is
21. 21.🔮 Predict: the adult irons for only one second. What happens? (a) it gets darker (b) the paper floats (c) writing stays faint (d) writing turns green
22. 22.🍋 Why does the lemon writing turn brown with heat? (a) the iron is brown (b) heat adds colour (c) the juice scorches first (d) paper turns lemony
23. 23.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it
24. 24.🧺 Do we need a cotton bud for the secret lemon message? (a) not needed (b) needed
25. 25.🍋 What colour does the lemon writing turn when an adult warms it? (a) green (b) brown (c) blue (d) white
26. 26.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) white paper (c) yeast (d) a cotton bud
27. 27.🧺 Do we need a battery cell for the secret lemon message? (a) needed (b) not needed
28. 28.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we measure it (b) we keep it the same (c) we change it
29. 29.True or false: putting the iron away is a job for an adult. (a) True (b) False
30. 30.True or false: yeast is needed for the secret lemon message. (a) False (b) True
31. 31.⚖️ 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
32. 32.🧺 Do we need a magnet for the secret lemon message? (a) needed (b) not needed
33. 33.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) lemon juice (c) a small bowl (d) a balloon
34. 34.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a mirror (c) lemon juice (d) a cotton bud
35. 35.⚖️ 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
36. 36.True or false: a balloon is not needed for the secret lemon message. (a) False (b) True
37. 37.True or false: a cotton bud is needed for the secret lemon message. (a) False (b) True
38. 38.True or false: ironing the paper is a job for an adult. (a) False (b) True
39. 39.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we change it (b) we measure it (c) we keep it the same
40. 40.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the iron setting (b) the ironing time (c) the kind of juice (d) how dark the writing is

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