Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 349 · 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.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) lemon juice (c) a small bowl (d) a mirror
2. 2.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) how dark the writing is (b) the kind of juice (c) the ironing time
3. 3.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we change it (b) we keep it the same (c) we measure it
4. 4.🧺 Do we need a battery cell for the secret lemon message? (a) needed (b) not needed
5. 5.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) ironing the paper (c) putting the iron away (d) writing the message
6. 6.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) turmeric powder (c) lemon juice (d) a magnet
7. 7.📘 The browning of lemon juice with heat is a ___ change. (a) physical (b) magnetic (c) musical (d) chemical
8. 8.🧺 Do we need an adult with an iron for the secret lemon message? (a) needed (b) not needed
9. 9.True or false: ironing the paper is a job for an adult. (a) True (b) False
10. 10.True or false: plugging in the iron is a job a child can do. (a) True (b) False
11. 11.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) reading the message (c) cutting the lemon (d) letting the paper dry
12. 12.True or false: white paper is not needed for the secret lemon message. (a) True (b) False
13. 13.🍋 Secret message: who does this step — plugging in the iron? (a) an adult does it (b) a child can do it
14. 14.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) lick your fingers (b) rub your eyes (c) skip washing (d) wash your hands
15. 15.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) reading the message (c) writing the message (d) plugging in the iron
16. 16.🍋 What colour does the lemon writing turn when an adult warms it? (a) blue (b) white (c) brown (d) green
17. 17.🛟 Why must children keep their fingers away from the iron? (a) it is sticky (b) it is magnetic (c) it can burn skin (d) it is cold
18. 18.True or false: an adult with an iron is not needed for the secret lemon message. (a) True (b) False
19. 19.⚖️ 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
20. 20.🧺 Which of these is not needed for the secret lemon message? (a) a battery cell (b) lemon juice (c) white paper (d) a cotton bud
21. 21.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the iron setting (b) how dark the writing is (c) the kind of juice
22. 22.True or false: putting the iron away is a job a child can do. (a) False (b) True
23. 23.⚖️ 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
24. 24.🧺 Do we need a magnet for the secret lemon message? (a) needed (b) not needed
25. 25.True or false: writing the message is a job a child can do. (a) False (b) True
26. 26.🍋 Secret message: who does this step — cutting the lemon? (a) a child can do it (b) an adult does it
27. 27.🧺 Which of these is not needed for the secret lemon message? (a) yeast (b) white paper (c) a cotton bud (d) an adult with an iron
28. 28.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) a rainbow (b) blue words (c) dark brown words (d) almost nothing
29. 29.True or false: cutting the lemon is a job a child can do. (a) True (b) False
30. 30.🧺 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) lemon juice (d) a magnet
31. 31.🍋 Secret message: who does this step — putting the iron away? (a) an adult does it (b) a child can do it
32. 32.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) turmeric powder (b) lemon juice (c) a cotton bud (d) an adult with an iron
33. 33.🔍 Which is the odd one out? (a) cutting the lemon (b) plugging in the iron (c) writing the message (d) putting the iron away
34. 34.True or false: a battery cell is needed for the secret lemon message. (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 ironing time (b) the same paper (c) the same cotton bud (d) how dark the writing is
36. 36.🛟 Who should use the hot iron in the secret message experiment? (a) the youngest child (b) any child (c) whoever is fastest (d) only an adult
37. 37.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a balloon (c) white paper (d) a small bowl
38. 38.🍋 Secret message: who does this step — letting the paper dry? (a) a child can do it (b) an adult does it
39. 39.🧺 Do we need lemon juice for the secret lemon message? (a) not needed (b) needed
40. 40.True or false: yeast is needed for the secret lemon message. (a) False (b) True

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