Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 950 · 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.True or false: letting the paper dry is a job for an adult. (a) True (b) False
2. 2.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) dark brown words (b) almost nothing (c) blue words (d) a rainbow
3. 3.🔍 Which is the odd one out? (a) writing the message (b) putting the iron away (c) letting the paper dry (d) reading the message
4. 4.⚖️ 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
5. 5.True or false: ironing the paper is a job a child can do. (a) False (b) True
6. 6.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) ironing the paper (c) letting the paper dry (d) writing the message
7. 7.🧺 Do we need turmeric powder for the secret lemon message? (a) needed (b) not needed
8. 8.⚖️ 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) how dark the writing is (c) the ironing time
9. 9.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) a small bowl (c) a magnet (d) white paper
10. 10.🛟 Who should use the hot iron in the secret message experiment? (a) whoever is fastest (b) any child (c) the youngest child (d) only an adult
11. 11.True or false: dipping the cotton bud is a job for an adult. (a) True (b) False
12. 12.🧺 Which of these is needed for the secret lemon message? (a) a cotton bud (b) turmeric powder (c) a balloon (d) a battery cell
13. 13.True or false: putting the iron away is a job for an adult. (a) False (b) True
14. 14.🔍 Which is the odd one out? (a) ironing the paper (b) writing the message (c) letting the paper dry (d) reading the message
15. 15.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) putting the iron away (c) cutting the lemon (d) writing the message
16. 16.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the same paper (b) the same cotton bud (c) the iron setting (d) the kind of juice
17. 17.🧺 Do we need a balloon for the secret lemon message? (a) needed (b) not needed
18. 18.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) lick your fingers (b) skip washing (c) wash your hands (d) rub your eyes
19. 19.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) letting the paper dry (c) putting the iron away (d) writing the message
20. 20.⚖️ 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 cotton bud (c) how dark the writing is
21. 21.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is kept the same. (a) True (b) False
22. 22.🔍 Which is the odd one out? (a) plugging in the iron (b) cutting the lemon (c) letting the paper dry (d) ironing the paper
23. 23.⚖️ 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 kind of juice (c) the iron setting
24. 24.True or false: turmeric powder is not needed for the secret lemon message. (a) False (b) True
25. 25.🍋 Secret message: who does this step — writing the message? (a) an adult does it (b) a child can do it
26. 26.⚖️ 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
27. 27.🔮 Predict: the adult irons for only one second. What happens? (a) it gets darker (b) writing stays faint (c) writing turns green (d) the paper floats
28. 28.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) letting the paper dry (c) plugging in the iron (d) writing the message
29. 29.🍋 Why does the lemon writing turn brown with heat? (a) heat adds colour (b) the juice scorches first (c) paper turns lemony (d) the iron is brown
30. 30.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) a balloon (c) a magnet (d) a small bowl
31. 31.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) a small bowl (c) white paper (d) a mirror
32. 32.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) cutting the lemon (c) dipping the cotton bud (d) putting the iron away
33. 33.⚖️ 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
34. 34.🔍 Which is the odd one out? (a) reading the message (b) plugging in the iron (c) ironing the paper (d) cutting the lemon
35. 35.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) yeast (c) a battery cell (d) white paper
36. 36.🍋 Secret message: who does this step — dipping the cotton bud? (a) an adult does it (b) a child can do it
37. 37.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) an adult with an iron (c) a battery cell (d) white paper
38. 38.True or false: a magnet is not needed for the secret lemon message. (a) True (b) False
39. 39.🔮 Can the brown writing go back to being invisible? (a) yes, if cooled (b) yes, if shaken (c) yes, in the dark (d) no, it stays brown
40. 40.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) a cotton bud (c) a balloon (d) an adult with an iron

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