Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 571 · 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) reading the message
2. 2.🧺 Do we need lemon juice for the secret lemon message? (a) needed (b) not needed
3. 3.True or false: dipping the cotton bud is a job for an adult. (a) True (b) False
4. 4.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) turmeric powder (c) a small bowl (d) a balloon
5. 5.True or false: plugging in the iron is a job a child can do. (a) True (b) False
6. 6.True or false: writing the message is a job for an adult. (a) True (b) False
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.🍋 Why does the lemon writing turn brown with heat? (a) paper turns lemony (b) the juice scorches first (c) heat adds colour (d) the iron is brown
9. 9.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we change it (b) we measure it (c) we keep it the same
10. 10.🔮 Can the brown writing go back to being invisible? (a) yes, if shaken (b) yes, in the dark (c) no, it stays brown (d) yes, if cooled
11. 11.🧺 Do we need white paper for the secret lemon message? (a) needed (b) not needed
12. 12.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is the one thing we change. (a) False (b) True
13. 13.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the same paper (b) the same cotton bud (c) the ironing time (d) how dark the writing is
14. 14.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it
15. 15.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) cutting the lemon (c) letting the paper dry (d) plugging in the iron
16. 16.🧺 Do we need a cotton bud for the secret lemon message? (a) not needed (b) needed
17. 17.🔍 Which is the odd one out? (a) letting the paper dry (b) ironing the paper (c) writing the message (d) dipping the cotton bud
18. 18.🍋 What colour does the lemon writing turn when an adult warms it? (a) brown (b) blue (c) white (d) green
19. 19.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) a small bowl (c) white paper (d) a battery cell
20. 20.🧺 Do we need a battery cell for the secret lemon message? (a) needed (b) not needed
21. 21.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) yeast (c) white paper (d) a magnet
22. 22.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we keep it the same (b) we change it (c) we measure it
23. 23.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) skip washing (b) lick your fingers (c) rub your eyes (d) wash your hands
24. 24.True or false: a small bowl is not needed for the secret lemon message. (a) True (b) False
25. 25.⚖️ 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
26. 26.True or false: a small bowl is needed for the secret lemon message. (a) True (b) False
27. 27.True or false: putting the iron away is a job for an adult. (a) False (b) True
28. 28.True or false: a battery cell is needed for the secret lemon message. (a) True (b) False
29. 29.True or false: an adult with an iron is needed for the secret lemon message. (a) True (b) False
30. 30.🛟 Why must children keep their fingers away from the iron? (a) it can burn skin (b) it is magnetic (c) it is sticky (d) it is cold
31. 31.⚖️ 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
32. 32.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) dark brown words (b) almost nothing (c) a rainbow (d) blue words
33. 33.⚖️ 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
34. 34.🧺 Do we need yeast for the secret lemon message? (a) needed (b) not needed
35. 35.True or false: turmeric powder is needed for the secret lemon message. (a) False (b) True
36. 36.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the iron setting (b) the kind of juice (c) the ironing time (d) the same cotton bud
37. 37.🛟 Who should use the hot iron in the secret message experiment? (a) whoever is fastest (b) only an adult (c) the youngest child (d) any child
38. 38.⚖️ 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
39. 39.🧺 Which of these is needed for the secret lemon message? (a) an adult with an iron (b) a balloon (c) a magnet (d) a battery cell
40. 40.🔍 Which is the odd one out? (a) letting the paper dry (b) dipping the cotton bud (c) reading the message (d) cutting the lemon

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