Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 756 · 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.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is what we measure. (a) False (b) True
2. 2.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) ironing the paper (c) plugging in the iron (d) writing the message
3. 3.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we measure it (b) we change it (c) we keep it the same
4. 4.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) a cotton bud (c) a battery cell (d) white paper
5. 5.🍋 Why does the lemon writing turn brown with heat? (a) paper turns lemony (b) the juice scorches first (c) the iron is brown (d) heat adds colour
6. 6.True or false: letting the paper dry is a job for an adult. (a) False (b) True
7. 7.🧺 Do we need a small bowl for the secret lemon message? (a) not needed (b) needed
8. 8.True or false: putting the iron away is a job for an adult. (a) True (b) False
9. 9.True or false: writing the message is a job a child can do. (a) True (b) False
10. 10.True or false: turmeric powder is needed for the secret lemon message. (a) False (b) True
11. 11.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) wash your hands (b) skip washing (c) rub your eyes (d) lick your fingers
12. 12.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) turmeric powder (c) a cotton bud (d) white paper
13. 13.🧺 Do we need an adult with an iron for the secret lemon message? (a) needed (b) not needed
14. 14.🛟 Who should use the hot iron in the secret message experiment? (a) only an adult (b) the youngest child (c) whoever is fastest (d) any child
15. 15.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a magnet (c) a cotton bud (d) a small bowl
16. 16.🧺 Which of these is needed for the secret lemon message? (a) white paper (b) yeast (c) a balloon (d) a mirror
17. 17.🍋 Secret message: who does this step — cutting the lemon? (a) an adult does it (b) a child can do it
18. 18.⚖️ 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) the iron setting (c) how dark the writing is
19. 19.⚖️ 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
20. 20.🍋 Which of these steps is a job for an adult? (a) ironing the paper (b) reading the message (c) writing the message (d) dipping the cotton bud
21. 21.🧺 Do we need white paper for the secret lemon message? (a) not needed (b) needed
22. 22.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we keep it the same (b) we measure it (c) we change it
23. 23.True or false: ironing the paper is a job for an adult. (a) False (b) True
24. 24.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) cutting the lemon (c) plugging in the iron (d) dipping the cotton bud
25. 25.🍋 Secret message: who does this step — writing the message? (a) a child can do it (b) an adult does it
26. 26.True or false: white paper is needed for the secret lemon message. (a) True (b) False
27. 27.⚖️ 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) how dark the writing is (c) the ironing time (d) the iron setting
28. 28.🛟 Why must children keep their fingers away from the iron? (a) it is magnetic (b) it is cold (c) it is sticky (d) it can burn skin
29. 29.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) a mirror (c) lemon juice (d) an adult with an iron
30. 30.🔍 Which is the odd one out? (a) dipping the cotton bud (b) letting the paper dry (c) writing the message (d) ironing the paper
31. 31.⚖️ 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
32. 32.True or false: plugging in the iron is a job for an adult. (a) False (b) True
33. 33.🔍 Which is the odd one out? (a) plugging in the iron (b) dipping the cotton bud (c) writing the message (d) reading the message
34. 34.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) an adult with an iron (c) turmeric powder (d) a battery cell
35. 35.🔍 Which is the odd one out? (a) dipping the cotton bud (b) writing the message (c) reading the message (d) putting the iron away
36. 36.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we change it (b) we measure it (c) we keep it the same
37. 37.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is kept the same. (a) False (b) True
38. 38.True or false: a balloon is not needed for the secret lemon message. (a) False (b) True
39. 39.True or false: a mirror is needed for the secret lemon message. (a) True (b) False
40. 40.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) dark brown words (b) a rainbow (c) blue words (d) almost nothing

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