Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 881 · 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: dipping the cotton bud is a job for an adult. (a) True (b) False
2. 2.🔍 Which is the odd one out? (a) letting the paper dry (b) ironing the paper (c) plugging in the iron (d) putting the iron away
3. 3.True or false: writing the message is a job a child can do. (a) True (b) False
4. 4.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a small bowl (c) lemon juice (d) a mirror
5. 5.🧺 Which of these is needed for the secret lemon message? (a) an adult with an iron (b) turmeric powder (c) yeast (d) a mirror
6. 6.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) ironing the paper (c) reading the message (d) putting the iron away
7. 7.True or false: a battery cell is needed for the secret lemon message. (a) True (b) False
8. 8.🔍 Which is the odd one out? (a) ironing the paper (b) writing the message (c) cutting the lemon (d) plugging in the iron
9. 9.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) yeast (c) a battery cell (d) a cotton bud
10. 10.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the ironing time (b) the kind of juice (c) how dark the writing is
11. 11.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) a balloon (c) lemon juice (d) white paper
12. 12.🛟 Why must children keep their fingers away from the iron? (a) it is cold (b) it can burn skin (c) it is sticky (d) it is magnetic
13. 13.⚖️ 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 same paper
14. 14.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is kept the same. (a) True (b) False
15. 15.True or false: writing the message is a job for an adult. (a) True (b) False
16. 16.⚖️ 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 paper (c) the ironing time (d) the kind of juice
17. 17.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a magnet (b) white paper (c) a cotton bud (d) lemon juice
18. 18.⚖️ 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 keep it the same (c) we measure it
19. 19.🍋 Secret message: who does this step — reading the message? (a) an adult does it (b) a child can do it
20. 20.🧺 Do we need turmeric powder for the secret lemon message? (a) needed (b) not needed
21. 21.True or false: letting the paper dry is a job a child can do. (a) False (b) True
22. 22.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) a mirror (c) a battery cell (d) white paper
23. 23.⚖️ 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
24. 24.🍋 Secret message: who does this step — writing the message? (a) an adult does it (b) a child can do it
25. 25.True or false: cutting the lemon is a job for an adult. (a) True (b) False
26. 26.🔍 Which is the odd one out? (a) plugging in the iron (b) putting the iron away (c) dipping the cotton bud (d) cutting the lemon
27. 27.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) dark brown words (b) a rainbow (c) almost nothing (d) blue words
28. 28.⚖️ 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) False (b) True
29. 29.🔍 Which is the odd one out? (a) reading the message (b) letting the paper dry (c) ironing the paper (d) dipping the cotton bud
30. 30.⚖️ 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
31. 31.🍋 Why does the lemon writing turn brown with heat? (a) the juice scorches first (b) heat adds colour (c) paper turns lemony (d) the iron is brown
32. 32.🧺 Do we need a cotton bud for the secret lemon message? (a) not needed (b) needed
33. 33.🧺 Which of these is not needed for the secret lemon message? (a) yeast (b) a cotton bud (c) white paper (d) a small bowl
34. 34.🍋 Secret message: who does this step — cutting the lemon? (a) a child can do it (b) an adult does it
35. 35.True or false: reading the message is a job for an adult. (a) True (b) False
36. 36.🔮 Predict: the adult irons for only one second. What happens? (a) writing turns green (b) the paper floats (c) it gets darker (d) writing stays faint
37. 37.⚖️ 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
38. 38.True or false: a balloon is needed for the secret lemon message. (a) True (b) False
39. 39.⚖️ 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
40. 40.🧺 Do we need yeast for the secret lemon message? (a) needed (b) not needed

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