Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 211 · 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 a child can do? (a) plugging in the iron (b) ironing the paper (c) putting the iron away (d) dipping the cotton bud
2. 2.🔍 Which is the odd one out? (a) writing the message (b) letting the paper dry (c) plugging in the iron (d) dipping the cotton bud
3. 3.🍋 Why can’t you see the lemon writing once it dries? (a) the paper ate it (b) the ink is magnetic (c) it turned into air (d) dry juice is see-through
4. 4.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) a battery cell (c) white paper (d) lemon juice
5. 5.🔮 Predict: the adult irons for only one second. What happens? (a) it gets darker (b) writing stays faint (c) the paper floats (d) writing turns green
6. 6.🧺 Do we need a magnet for the secret lemon message? (a) not needed (b) needed
7. 7.🍋 Secret message: who does this step — letting the paper dry? (a) an adult does it (b) a child can do it
8. 8.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) cutting the lemon (c) plugging in the iron (d) reading the message
9. 9.🔮 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
10. 10.True or false: letting the paper dry is a job for an adult. (a) False (b) True
11. 11.🔍 Which is the odd one out? (a) putting the iron away (b) cutting the lemon (c) writing the message (d) ironing the paper
12. 12.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) letting the paper dry (c) writing the message (d) cutting the lemon
13. 13.🔍 Which is the odd one out? (a) ironing the paper (b) cutting the lemon (c) dipping the cotton bud (d) putting the iron away
14. 14.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a cotton bud (c) turmeric powder (d) white paper
15. 15.⚖️ 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 same cotton bud (c) the kind of juice (d) the iron setting
16. 16.🧺 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 balloon
17. 17.True or false: ironing the paper is a job a child can do. (a) True (b) False
18. 18.🧺 Do we need turmeric powder for the secret lemon message? (a) needed (b) not needed
19. 19.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is kept the same. (a) True (b) False
20. 20.🧺 Do we need white paper for the secret lemon message? (a) not needed (b) needed
21. 21.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we measure it (b) we keep it the same (c) we change it
22. 22.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it
23. 23.🍋 Secret message: who does this step — ironing the paper? (a) an adult does it (b) a child can do it
24. 24.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) yeast (b) a cotton bud (c) a small bowl (d) lemon juice
25. 25.⚖️ 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 iron setting
26. 26.🔮 Can the brown writing go back to being invisible? (a) yes, in the dark (b) yes, if shaken (c) no, it stays brown (d) yes, if cooled
27. 27.🍋 Which of these steps is a job for an adult? (a) reading the message (b) writing the message (c) putting the iron away (d) dipping the cotton bud
28. 28.🍋 Why does the lemon writing turn brown with heat? (a) the iron is brown (b) paper turns lemony (c) the juice scorches first (d) heat adds colour
29. 29.True or false: yeast is needed for the secret lemon message. (a) False (b) True
30. 30.⚖️ 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 change it (c) we measure it
31. 31.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) a mirror (c) turmeric powder (d) an adult with an iron
32. 32.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) letting the paper dry (c) cutting the lemon (d) ironing the paper
33. 33.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) lick your fingers (b) skip washing (c) rub your eyes (d) wash your hands
34. 34.True or false: dipping the cotton bud is a job a child can do. (a) True (b) False
35. 35.True or false: lemon juice is not needed for the secret lemon message. (a) True (b) False
36. 36.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is kept the same. (a) False (b) True
37. 37.🧺 Do we need yeast for the secret lemon message? (a) not needed (b) needed
38. 38.True or false: an adult with an iron is not needed for the secret lemon message. (a) False (b) True
39. 39.🛟 Who should use the hot iron in the secret message experiment? (a) any child (b) the youngest child (c) whoever is fastest (d) only an adult
40. 40.True or false: a magnet is needed for the secret lemon message. (a) False (b) True

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