Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 912 · 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 is the odd one out? (a) reading the message (b) dipping the cotton bud (c) putting the iron away (d) writing the message
2. 2.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) lemon juice (c) a cotton bud (d) a battery cell
3. 3.⚖️ 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
4. 4.🛟 Who should use the hot iron in the secret message experiment? (a) whoever is fastest (b) the youngest child (c) any child (d) only an adult
5. 5.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a magnet (b) a small bowl (c) white paper (d) lemon juice
6. 6.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) white paper (c) a small bowl (d) turmeric powder
7. 7.🔮 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
8. 8.True or false: letting the paper dry is a job a child can do. (a) True (b) False
9. 9.🍋 Which of these steps is a job a child can do? (a) letting the paper dry (b) putting the iron away (c) cutting the lemon (d) ironing the paper
10. 10.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) white paper (c) a balloon (d) lemon juice
11. 11.🧺 Do we need turmeric powder for the secret lemon message? (a) needed (b) not needed
12. 12.🧺 Do we need a cotton bud for the secret lemon message? (a) not needed (b) needed
13. 13.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) lick your fingers (b) rub your eyes (c) wash your hands (d) skip washing
14. 14.⚖️ 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) False (b) True
15. 15.🧺 Do we need lemon juice for the secret lemon message? (a) needed (b) not needed
16. 16.⚖️ 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 change it (c) we keep it the same
17. 17.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) yeast (c) white paper (d) an adult with an iron
18. 18.⚖️ 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 ironing time (c) the kind of juice (d) the iron setting
19. 19.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we measure it (b) we keep it the same (c) we change it
20. 20.🍋 Which of these steps is a job for an adult? (a) plugging in the iron (b) letting the paper dry (c) reading the message (d) dipping the cotton bud
21. 21.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is kept the same. (a) False (b) True
22. 22.🧺 Do we need white paper for the secret lemon message? (a) needed (b) not needed
23. 23.True or false: putting the iron away is a job for an adult. (a) False (b) True
24. 24.🍋 Which of these steps is a job for an adult? (a) reading the message (b) dipping the cotton bud (c) letting the paper dry (d) cutting the lemon
25. 25.True or false: a balloon is needed for the secret lemon message. (a) False (b) True
26. 26.🧺 Do we need yeast for the secret lemon message? (a) not needed (b) needed
27. 27.🧺 Do we need a battery cell for the secret lemon message? (a) needed (b) not needed
28. 28.🔮 Can the brown writing go back to being invisible? (a) yes, in the dark (b) no, it stays brown (c) yes, if shaken (d) yes, if cooled
29. 29.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is kept the same. (a) False (b) True
30. 30.🧺 Do we need a small bowl for the secret lemon message? (a) not needed (b) needed
31. 31.True or false: white paper is not needed for the secret lemon message. (a) False (b) True
32. 32.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it
33. 33.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) a balloon (c) turmeric powder (d) white paper
34. 34.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) ironing the paper (c) dipping the cotton bud (d) cutting the lemon
35. 35.True or false: a cotton bud is needed for the secret lemon message. (a) False (b) True
36. 36.True or false: yeast is needed for the secret lemon message. (a) True (b) False
37. 37.🔍 Which is the odd one out? (a) reading the message (b) cutting the lemon (c) plugging in the iron (d) ironing the paper
38. 38.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) a cotton bud (c) a small bowl (d) a magnet
39. 39.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) almost nothing (b) dark brown words (c) a rainbow (d) blue words
40. 40.True or false: a cotton bud is not needed for the secret lemon message. (a) False (b) True

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