Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 169 · 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.🧺 Do we need a mirror for the secret lemon message? (a) needed (b) not needed
2. 2.⚖️ 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 same cotton bud (c) the same paper (d) the kind of juice
3. 3.True or false: white paper is not needed for the secret lemon message. (a) True (b) False
4. 4.🧺 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) white paper (d) a mirror
5. 5.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
6. 6.🔍 Which is the odd one out? (a) dipping the cotton bud (b) reading the message (c) writing the message (d) ironing the paper
7. 7.🍋 Secret message: who does this step — dipping the cotton bud? (a) an adult does it (b) a child can do it
8. 8.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we keep it the same (b) we change it (c) we measure it
9. 9.⚖️ 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
10. 10.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) turmeric powder (c) a battery cell (d) white paper
11. 11.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the iron setting (b) the kind of juice (c) how dark the writing is
12. 12.🍋 Secret message: who does this step — reading the message? (a) an adult does it (b) a child can do it
13. 13.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) an adult with an iron (c) a small bowl (d) yeast
14. 14.🔮 Can the brown writing go back to being invisible? (a) yes, if shaken (b) no, it stays brown (c) yes, in the dark (d) yes, if cooled
15. 15.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we measure it (b) we change it (c) we keep it the same
16. 16.🍋 Secret message: who does this step — letting the paper dry? (a) a child can do it (b) an adult does it
17. 17.🍋 Which of these steps is a job a child can do? (a) letting the paper dry (b) ironing the paper (c) plugging in the iron (d) cutting the lemon
18. 18.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is kept the same. (a) True (b) False
19. 19.🧺 Do we need white paper for the secret lemon message? (a) needed (b) not needed
20. 20.📘 The browning of lemon juice with heat is a ___ change. (a) chemical (b) physical (c) magnetic (d) musical
21. 21.🧺 Do we need a magnet for the secret lemon message? (a) not needed (b) needed
22. 22.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) how dark the writing is (b) the ironing time (c) the kind of juice (d) the iron setting
23. 23.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is what we measure. (a) False (b) True
24. 24.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we change it (b) we measure it (c) we keep it the same
25. 25.🍋 What colour does the lemon writing turn when an adult warms it? (a) brown (b) white (c) green (d) blue
26. 26.🍋 Secret message: who does this step — plugging in the iron? (a) an adult does it (b) a child can do it
27. 27.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it
28. 28.🔮 Predict: the adult irons for only one second. What happens? (a) writing turns green (b) the paper floats (c) writing stays faint (d) it gets darker
29. 29.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) white paper (c) a cotton bud (d) a balloon
30. 30.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we measure it (b) we change it (c) we keep it the same
31. 31.🧺 Which of these is needed for the secret lemon message? (a) a small bowl (b) yeast (c) a mirror (d) a battery cell
32. 32.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is what we measure. (a) True (b) False
33. 33.🔍 Which is the odd one out? (a) reading the message (b) writing the message (c) letting the paper dry (d) putting the iron away
34. 34.⚖️ 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 change it (c) we keep it the same
35. 35.True or false: a battery cell is needed for the secret lemon message. (a) False (b) True
36. 36.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) a cotton bud (c) lemon juice (d) a magnet
37. 37.🍋 Which of these steps is a job for an adult? (a) writing the message (b) dipping the cotton bud (c) letting the paper dry (d) putting the iron away
38. 38.True or false: lemon juice is needed for the secret lemon message. (a) False (b) True
39. 39.🔍 Which is the odd one out? (a) putting the iron away (b) cutting the lemon (c) ironing the paper (d) letting the paper dry
40. 40.🛟 Who should use the hot iron in the secret message experiment? (a) any child (b) the youngest child (c) only an adult (d) whoever is fastest

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