Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 370 · 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.🛟 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
2. 2.🧺 Do we need a balloon for the secret lemon message? (a) not needed (b) needed
3. 3.📘 The browning of lemon juice with heat is a ___ change. (a) physical (b) musical (c) chemical (d) magnetic
4. 4.🍋 Secret message: who does this step — writing the message? (a) a child can do it (b) an adult does it
5. 5.🔍 Which is the odd one out? (a) putting the iron away (b) ironing the paper (c) reading the message (d) plugging in the iron
6. 6.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a cotton bud (c) a magnet (d) an adult with an iron
7. 7.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we keep it the same (b) we change it (c) we measure it
8. 8.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is kept the same. (a) True (b) False
9. 9.True or false: dipping the cotton bud is a job a child can do. (a) False (b) True
10. 10.⚖️ 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
11. 11.🍋 What colour does the lemon writing turn when an adult warms it? (a) blue (b) white (c) green (d) brown
12. 12.True or false: letting the paper dry is a job for an adult. (a) False (b) True
13. 13.🍋 Which of these steps is a job for an adult? (a) plugging in the iron (b) letting the paper dry (c) dipping the cotton bud (d) reading the message
14. 14.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we measure it (b) we keep it the same (c) we change it
15. 15.🧺 Do we need white paper for the secret lemon message? (a) not needed (b) needed
16. 16.True or false: dipping the cotton bud is a job for an adult. (a) True (b) False
17. 17.🧺 Do we need a battery cell for the secret lemon message? (a) needed (b) not needed
18. 18.🍋 Why can’t you see the lemon writing once it dries? (a) it turned into air (b) dry juice is see-through (c) the ink is magnetic (d) the paper ate it
19. 19.🧺 Do we need a mirror for the secret lemon message? (a) not needed (b) needed
20. 20.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a cotton bud (c) a small bowl (d) yeast
21. 21.🛟 Why must children keep their fingers away from the iron? (a) it is cold (b) it is sticky (c) it is magnetic (d) it can burn skin
22. 22.🍋 Which of these steps is a job a child can do? (a) letting the paper dry (b) plugging in the iron (c) putting the iron away (d) cutting the lemon
23. 23.True or false: a small bowl is not needed for the secret lemon message. (a) True (b) False
24. 24.🛟 Who should use the hot iron in the secret message experiment? (a) the youngest child (b) whoever is fastest (c) only an adult (d) any child
25. 25.🔍 Which is the odd one out? (a) cutting the lemon (b) writing the message (c) putting the iron away (d) ironing the paper
26. 26.🔍 Which is the odd one out? (a) writing the message (b) dipping the cotton bud (c) putting the iron away (d) letting the paper dry
27. 27.🔮 Predict: the adult irons for only one second. What happens? (a) the paper floats (b) writing stays faint (c) it gets darker (d) writing turns green
28. 28.🧺 Do we need turmeric powder for the secret lemon message? (a) not needed (b) needed
29. 29.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) almost nothing (b) dark brown words (c) blue words (d) a rainbow
30. 30.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) reading the message (c) putting the iron away (d) plugging in the iron
31. 31.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) reading the message (c) ironing the paper (d) writing the message
32. 32.⚖️ 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
33. 33.🧺 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 mirror
34. 34.🍋 Secret message: who does this step — cutting the lemon? (a) a child can do it (b) an adult does it
35. 35.⚖️ 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
36. 36.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the ironing time (b) how dark the writing is (c) the kind of juice (d) the same cotton bud
37. 37.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) a balloon (c) an adult with an iron (d) a cotton bud
38. 38.⚖️ 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
39. 39.True or false: white paper is needed for the secret lemon message. (a) False (b) True
40. 40.🍋 Secret message: who does this step — letting the paper dry? (a) an adult does it (b) a child can do it

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