Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 951 · 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) a rainbow (b) dark brown words (c) blue words (d) almost nothing
2. 2.🧺 Do we need turmeric powder for the secret lemon message? (a) needed (b) not needed
3. 3.🧺 Do we need white paper for the secret lemon message? (a) not needed (b) needed
4. 4.🧺 Do we need a battery cell for the secret lemon message? (a) needed (b) not needed
5. 5.True or false: plugging in the iron is a job for an adult. (a) True (b) False
6. 6.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is the one thing we change. (a) True (b) False
7. 7.🧺 Do we need a small bowl for the secret lemon message? (a) not needed (b) needed
8. 8.True or false: a magnet is not needed for the secret lemon message. (a) False (b) True
9. 9.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the same cotton bud (b) the iron setting (c) the kind of juice (d) how dark the writing is
10. 10.🧺 Do we need a magnet for the secret lemon message? (a) needed (b) not needed
11. 11.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) a balloon (c) white paper (d) an adult with an iron
12. 12.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a magnet (b) a small bowl (c) lemon juice (d) white paper
13. 13.🔍 Which is the odd one out? (a) writing the message (b) dipping the cotton bud (c) ironing the paper (d) reading the message
14. 14.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) skip washing (b) lick your fingers (c) wash your hands (d) rub your eyes
15. 15.⚖️ 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
16. 16.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is the one thing we change. (a) False (b) True
17. 17.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) letting the paper dry (c) ironing the paper (d) cutting the lemon
18. 18.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) an adult with an iron (c) yeast (d) a small bowl
19. 19.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) an adult with an iron (c) lemon juice (d) a battery cell
20. 20.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) a battery cell (c) a balloon (d) lemon juice
21. 21.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we keep it the same (b) we change it (c) we measure it
22. 22.True or false: a small bowl is needed for the secret lemon message. (a) False (b) True
23. 23.🍋 Why can’t you see the lemon writing once it dries? (a) it turned into air (b) the paper ate it (c) the ink is magnetic (d) dry juice is see-through
24. 24.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) writing the message (c) cutting the lemon (d) putting the iron away
25. 25.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the kind of juice (b) how dark the writing is (c) the same cotton bud (d) the iron setting
26. 26.True or false: dipping the cotton bud is a job for an adult. (a) False (b) True
27. 27.🛟 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
28. 28.🍋 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
29. 29.🔍 Which is the odd one out? (a) reading the message (b) cutting the lemon (c) dipping the cotton bud (d) writing the message
30. 30.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is kept the same. (a) True (b) False
31. 31.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is kept the same. (a) True (b) False
32. 32.🔍 Which is the odd one out? (a) putting the iron away (b) cutting the lemon (c) dipping the cotton bud (d) plugging in the iron
33. 33.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is the one thing we change. (a) False (b) True
34. 34.True or false: a cotton bud is needed for the secret lemon message. (a) True (b) False
35. 35.⚖️ 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) True (b) False
36. 36.🧺 Do we need a mirror for the secret lemon message? (a) not needed (b) needed
37. 37.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) a mirror (c) a small bowl (d) yeast
38. 38.🍋 Which of these steps is a job for an adult? (a) ironing the paper (b) letting the paper dry (c) reading the message (d) writing the message
39. 39.True or false: lemon juice is not needed for the secret lemon message. (a) False (b) True
40. 40.🧺 Do we need lemon juice for the secret lemon message? (a) not needed (b) needed

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