Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 567 · 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) putting the iron away (c) ironing the paper (d) dipping the cotton bud
2. 2.🍋 Secret message: who does this step — reading the message? (a) an adult does it (b) a child can do it
3. 3.🍋 Secret message: who does this step — dipping the cotton bud? (a) an adult does it (b) a child can do it
4. 4.📘 The browning of lemon juice with heat is a ___ change. (a) musical (b) chemical (c) physical (d) magnetic
5. 5.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) an adult with an iron (c) a mirror (d) a cotton bud
6. 6.True or false: dipping the cotton bud is a job for an adult. (a) True (b) False
7. 7.🧺 Do we need a battery cell for the secret lemon message? (a) needed (b) not needed
8. 8.🔍 Which is the odd one out? (a) putting the iron away (b) cutting the lemon (c) dipping the cotton bud (d) ironing the paper
9. 9.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it
10. 10.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) a mirror (c) turmeric powder (d) a small bowl
11. 11.True or false: writing the message is a job for an adult. (a) False (b) True
12. 12.🔮 Predict: the adult irons for only one second. What happens? (a) writing stays faint (b) writing turns green (c) it gets darker (d) the paper floats
13. 13.True or false: letting the paper dry is a job for an adult. (a) True (b) False
14. 14.🛟 Why must children keep their fingers away from the iron? (a) it is magnetic (b) it is sticky (c) it is cold (d) it can burn skin
15. 15.True or false: a magnet is needed for the secret lemon message. (a) True (b) False
16. 16.🍋 Why does the lemon writing turn brown with heat? (a) paper turns lemony (b) heat adds colour (c) the juice scorches first (d) the iron is brown
17. 17.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the same cotton bud (b) the kind of juice (c) how dark the writing is
18. 18.True or false: dipping the cotton bud is a job a child can do. (a) False (b) True
19. 19.🍋 Secret message: who does this step — letting the paper dry? (a) a child can do it (b) an adult does it
20. 20.🛟 Who should use the hot iron in the secret message experiment? (a) the youngest child (b) only an adult (c) any child (d) whoever is fastest
21. 21.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a battery cell (c) white paper (d) an adult with an iron
22. 22.🧺 Do we need turmeric powder for the secret lemon message? (a) not needed (b) needed
23. 23.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) lick your fingers (b) wash your hands (c) rub your eyes (d) skip washing
24. 24.⚖️ 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 ironing time (c) how dark the writing is (d) the kind of juice
25. 25.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) a battery cell (c) an adult with an iron (d) lemon juice
26. 26.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) a cotton bud (c) a magnet (d) lemon juice
27. 27.True or false: turmeric powder is not needed for the secret lemon message. (a) False (b) True
28. 28.🔮 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
29. 29.🔍 Which is the odd one out? (a) reading the message (b) putting the iron away (c) plugging in the iron (d) cutting the lemon
30. 30.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a cotton bud (c) yeast (d) an adult with an iron
31. 31.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the ironing time (b) how dark the writing is (c) the kind of juice
32. 32.⚖️ 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 keep it the same (c) we change it
33. 33.🧺 Which of these is needed for the secret lemon message? (a) white paper (b) a balloon (c) a mirror (d) a magnet
34. 34.⚖️ 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
35. 35.⚖️ 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 ironing time (c) the iron setting (d) how dark the writing is
36. 36.🧺 Do we need a mirror for the secret lemon message? (a) not needed (b) needed
37. 37.🔍 Which is the odd one out? (a) ironing the paper (b) cutting the lemon (c) writing the message (d) putting the iron away
38. 38.🧺 Do we need a balloon for the secret lemon message? (a) not needed (b) needed
39. 39.True or false: lemon juice is not needed for the secret lemon message. (a) True (b) False
40. 40.True or false: an adult with an iron is not needed for the secret lemon message. (a) False (b) True

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